How to choose a probiotic: quality markers vs warning signs for C. diff prevention

Could diarrhoea on itraconazole be C. diff?

Last reviewed: 20 April 2026

Understanding the difference for people with aspergillosis

Key points

  • Clostridioides difficile (C. diff) is a bowel infection most often linked to antibiotic use, not antifungal treatment.
  • Itraconazole can cause diarrhoea and stomach upset as a recognised side effect, but that is not the same as having C. diff.
  • People with aspergillosis may still be at higher risk of C. diff because many have had recent antibiotics, repeated antibiotic courses, hospital care, or other illnesses.
  • Persistent watery diarrhoea, tummy pain, fever, bleeding, dehydration, or diarrhoea lasting more than a few days should not be ignored.
  • Probiotics may help some people reduce antibiotic-associated diarrhoea, but they are not suitable for everyone and are not a treatment for C. diff.

Contents

Why this question comes up so often

If you live with aspergillosis, it can be hard to work out why new symptoms have appeared. Many patients have had antibiotics at some point for chest infections, have been in hospital, or take several medicines at once. So when diarrhoea develops while on itraconazole, it is understandable to wonder whether the antifungal is to blame, whether it is a simple side effect, or whether something more important is going on.

That confusion is common, because several different problems can cause similar gut symptoms.

What is C. diff?

Clostridioides difficile (C. diff) is a bacterium that can infect the bowel and cause diarrhoea, abdominal pain and sometimes much more severe illness. It often affects people whose usual gut bacteria have been disrupted, especially after antibiotic use.

Some people carry C. diff without symptoms, but when the balance of the gut changes, the bacteria can multiply and produce toxins that irritate and inflame the bowel. That is why C. diff is more than “just diarrhoea”. It is a specific infection with recognised causes and recognised risks.

Is itraconazole a usual cause of C. diff?

In general, no. Itraconazole is an antifungal, not an antibiotic, and it is not recognised as a typical trigger for C. diff. Most guidance links C. diff mainly to antibiotics, especially in people who are older, frailer, recently hospitalised, or otherwise vulnerable.

That said, itraconazole can cause gastrointestinal side effects, including diarrhoea. So someone may genuinely develop bowel symptoms while taking itraconazole without having C. diff.

The important point is this: diarrhoea on itraconazole does not automatically mean C. diff, but it should not automatically be dismissed as “just the antifungal” either.

Why people with aspergillosis may still worry about C. diff

Even if itraconazole is not the usual cause, people with aspergillosis may still face a real risk of C. diff because many have had one or more recognised risk factors:

  • recent or repeated antibiotic courses
  • recent hospital stay or healthcare exposure
  • older age
  • other illnesses or frailty
  • sometimes medicines such as proton pump inhibitors have also been associated with increased risk

So in practice, a patient may be taking itraconazole when diarrhoea starts, but the bigger driver may actually be a recent antibiotic course or hospital admission rather than the antifungal itself.

Side effect or infection?

Here is the distinction many patients find helpful.

Diarrhoea more suggestive of a medicine side effect

A simple side effect from itraconazole may cause:

  • looser stools
  • nausea
  • abdominal discomfort
  • symptoms that are unpleasant but relatively mild and not rapidly worsening

Diarrhoea more concerning for C. diff or another bowel infection

Symptoms that deserve proper attention include:

  • frequent watery diarrhoea
  • tummy pain or cramping
  • fever
  • blood in the stool or bleeding from the bottom
  • dehydration, such as very dry mouth, dizziness, or passing very little urine
  • diarrhoea lasting more than 7 days
  • feeling generally very unwell
More suggestive of side effect More concerning for infection such as C. diff
Mild diarrhoea or looser stools Frequent watery diarrhoea
Mild nausea or stomach discomfort Tummy pain, cramping, fever
Symptoms remain mild Symptoms worsening or lasting several days
No bleeding or dehydration Bleeding, dehydration, or feeling very unwell

In other words, the pattern and severity matter. Mild stomach upset can happen with many medicines. Persistent watery diarrhoea, pain, fever or bleeding should not simply be written off as “one of those things”.

What do NHS sources advise?

NHS advice is to seek urgent help if diarrhoea happens while taking, or after recently taking, antibiotics, if there is blood in the diarrhoea, or if it lasts more than 7 days. Severe pain, fever, or signs of dehydration are also warning signs.

This matters because true C. diff is a recognised medical problem with specific treatment pathways.

Do probiotics help?

Probiotics are products that contain live microorganisms (usually bacteria or yeast) intended to support the balance of the gut microbiome. They are often sold as capsules, powders, or drinks.

They are widely available, but their role in preventing or managing diarrhoea is still being studied, and product quality varies considerably.

What does the evidence suggest?

  • Some studies suggest probiotics may help reduce antibiotic-associated diarrhoea.
  • There is some evidence they may reduce the risk of C. diff in certain situations, particularly when started early during antibiotic treatment.
  • However, results are inconsistent, and benefits are usually modest.

Are probiotics a treatment for C. diff?

No. Probiotics are not a standard treatment for confirmed C. diff infection. Medical treatment is required for confirmed cases.

How to recognise a higher-quality probiotic

If people are considering probiotics, it can be helpful to understand what distinguishes more credible products from less reliable ones.

  • Clearly labelled strains – for example Lactobacillus rhamnosus GG rather than just “Lactobacillus”. Evidence is strain-specific.
  • CFU count (colony forming units) – this indicates the number of live organisms. Typical products range from millions to billions of CFU.
  • Expiry-date guarantee – reputable products state the number of live organisms at the end of shelf life, not just “at manufacture”.
  • Storage instructions – some require refrigeration; unclear instructions may suggest lower quality control.
  • Evidence transparency – more reliable manufacturers refer to published studies rather than making vague claims.

Common red flags to be cautious about

  • Claims to “cure” or “prevent” serious conditions such as C. diff
  • Very long lists of ingredients without clear strain identification
  • No CFU count or unclear labelling
  • Heavy marketing language such as “miracle”, “detox”, or “boosts immunity dramatically”
  • Products sold only through social media or unverified online sources

Are probiotics safe for everyone?

Probiotics are often well tolerated, but they are not suitable for everyone.

  • People who are immunocompromised or seriously unwell may be at risk of rare infections linked to probiotic organisms.
  • This includes some patients with complex lung disease, those on immunosuppressive treatment, or those with central lines.
  • Because of this, probiotics should be discussed with a healthcare professional before use in these groups.

What is the practical take?

  • Probiotics may help some people reduce diarrhoea associated with antibiotics.
  • They are not routinely recommended for everyone.
  • They are not a treatment for C. diff.
  • Product quality varies, so understanding labels is important.
  • For people with long-term conditions such as aspergillosis, it is sensible to check before using them.

As research into the gut microbiome develops, understanding of probiotics may improve. For now, they are best seen as a possible supportive option in some situations, rather than a standard part of care.

Common questions

Can antifungals cause C. diff?

Not usually. The main recognised trigger is antibiotic exposure, not antifungal therapy. But antifungals such as itraconazole can cause diarrhoea as a side effect, which can create understandable confusion.

Could I get C. diff if I have not had antibiotics recently?

Yes, it is possible, but antibiotics are the classic and most important risk factor. Recent hospital contact and other vulnerabilities can matter too.

If my diarrhoea started after itraconazole, does that prove itraconazole caused it?

No. Timing can be a clue, but it does not prove the cause. A side effect is possible, but so are other explanations, including infection, recent antibiotics, other medicines, or unrelated bowel problems.

Could acid-suppressing tablets increase risk?

Possibly. Proton pump inhibitors have been associated with C. diff risk in some studies, but that does not prove they directly cause it.

Why this matters in aspergillosis

For aspergillosis patients, this topic matters for two reasons.

First, gut symptoms are common, especially when treatment is complex. That makes it easy to mislabel symptoms. Second, many patients have also needed antibiotics for chest infections or have had hospital admissions, which means true C. diff risk may be more relevant than it first appears.

The safest message is not “itraconazole causes C. diff” and not “it is definitely nothing serious”, but rather: know the difference, notice the red flags, and get persistent symptoms checked.

When to seek medical advice

Seek medical advice promptly if diarrhoea is:

  • frequent and watery
  • continuing rather than settling
  • happening after recent antibiotics
  • accompanied by tummy pain, fever, bleeding, or dehydration
  • making you feel significantly unwell

Take-home message

Long-term itraconazole use is not a typical direct cause of C. diff. However, itraconazole can cause diarrhoea, and people with aspergillosis may still be at risk of C. diff because of recent antibiotics, hospital exposure, and other health factors.

The key is not to jump to conclusions either way: mild diarrhoea can be a medicine side effect, but persistent watery diarrhoea, pain, fever, bleeding or dehydration should be taken seriously.

References

  1. NHS. Clostridioides difficile (C. diff) infection.
  2. NICE. Clostridioides difficile infection: antimicrobial prescribing (NG199).
  3. BNF. Itraconazole.
  4. UK Health Security Agency. Clostridioides difficile guidance, data and analysis.
  5. UK Health Security Agency. Increase in Clostridioides difficile infections: current epidemiology data and investigations.

Author: National Aspergillosis Centre CARES Team

by GAtherton

What if you can’t tolerate azole antifungal medicines?

Last reviewed: April 2026

Key points

  • Azole antifungals are commonly used to treat aspergillosis, but not everyone tolerates them well.
  • “Azole intolerance” means the body reacts badly to the medication, even if it is otherwise effective.
  • Symptoms can include fatigue, flushing, shaking, nausea, and discomfort around the liver area.
  • In some cases, blood tests show changes in liver function.
  • If azoles are not tolerated, there are often alternative approaches your clinical team can consider.

Contents

What are azole antifungals?

Azole antifungals are a group of medicines used to treat fungal infections such as aspergillosis. They work by interfering with the fungal cell membrane, helping to stop the fungus growing.

Common examples include:

  • Fluconazole
  • Itraconazole
  • Voriconazole
  • Posaconazole

They are often used long-term in conditions like chronic pulmonary aspergillosis (CPA) or allergic bronchopulmonary aspergillosis (ABPA).

What is azole intolerance?

Azole intolerance means that a person develops unpleasant or harmful side effects when taking these medications, even at standard doses.

This is different from:

  • Allergy – an immune reaction (e.g. rash, swelling, breathing difficulty)
  • Resistance – when the fungus is not affected by the drug

With intolerance, the drug may still work against the fungus—but the body cannot tolerate its effects.

Why does azole intolerance happen?

There is no single cause. Instead, several factors can contribute:

1. How the body processes the drug

Azoles are broken down in the liver. People vary in how efficiently this happens, which can lead to higher levels of the drug in the body.

2. Effects on liver enzymes

Azoles affect enzymes (called cytochrome P450 enzymes) that are involved in processing many medications. This can:

  • Increase drug levels
  • Cause interactions with other medications
  • Put strain on the liver

3. Individual sensitivity

Some people are simply more sensitive to these drugs, even when blood levels are within the expected range.

4. Other health factors

  • Existing liver conditions
  • Age
  • Other medications
  • Nutritional status

Common symptoms to look out for

Patients describe a range of symptoms when azoles are not well tolerated, including:

  • Flushed or hot cheeks
  • Shaking or tremor
  • Severe fatigue
  • Nausea or reduced appetite
  • Discomfort or pain in the upper abdomen, back, or sides (where the liver sits)
  • General feeling of being unwell

These symptoms can appear soon after starting treatment or develop over time.

The role of the liver

The liver plays a central role in processing azole antifungals.

In some cases, this can lead to:

  • Raised liver enzymes on blood tests
  • Inflammation or irritation of the liver

It is important to note that:

  • Some people have abnormal blood tests without symptoms
  • Others feel unwell even when tests are only mildly changed

This is why both symptoms and blood tests are considered together.

What can be done if azoles are not tolerated?

If azole intolerance is suspected, your clinical team may consider several approaches:

Adjusting treatment

  • Reducing the dose
  • Changing how the medication is taken (e.g. with food)

Switching to another azole

Some people tolerate one azole better than another.

Therapeutic drug monitoring (TDM)

Blood tests can measure drug levels to help ensure they are not too high or too low.

Considering non-azole treatments

In some cases, different classes of antifungal medication may be considered.

The best approach depends on the individual, the condition being treated, and how severe the side effects are.

Why monitoring is important

Because azoles affect the liver and interact with other medications, monitoring is a routine part of care.

This may include:

  • Regular liver function blood tests
  • Drug level monitoring (for some azoles)
  • Review of other medications

Monitoring helps detect problems early and allows treatment to be adjusted safely.

Common questions

Does intolerance mean I cannot take any antifungal treatment?

No. Many patients who cannot tolerate one medication can use another, or a different approach may be possible.

Will the symptoms settle if I continue?

In some cases mild symptoms improve, but persistent or worsening symptoms should always be reviewed.

Is this common?

Most people tolerate azoles reasonably well, but intolerance is recognised and not rare in specialist clinics.

When to seek medical advice

You should contact your healthcare team if you experience:

  • Persistent or worsening fatigue
  • Pain in the upper abdomen, back, or sides
  • Nausea affecting eating or drinking
  • New or unusual symptoms after starting medication

Seek urgent medical attention if you notice:

  • Yellowing of the skin or eyes (jaundice)
  • Dark urine or pale stools
  • Severe abdominal pain

Summary

Azole antifungals are an important part of treating aspergillosis, but some people experience intolerance.

This is usually related to how the body processes the medication—particularly in the liver—and varies from person to person.

If intolerance occurs, it does not mean that treatment options have run out. With careful monitoring and specialist input, alternative strategies can often be found.

Further reading

Author & review

This article has been prepared for patients and carers using information aligned with UK specialist practice, including the National Aspergillosis Centre (Manchester, UK).

Important: This content is for general educational purposes only and is not a substitute for medical advice. Always speak to your healthcare team about your own situation.

by GAtherton

Inflammation and Aspergillosis: Understanding “Stable”, “Flare”, and “Improving” Disease

Last reviewed: April 2026

Key points

  • Inflammation is part of the body’s response to Aspergillus, but it does not always mean damage is actively worsening.
  • “Stable” disease means no clear progression over time, not that the condition has disappeared.
  • Symptoms in aspergillosis often vary because of other infections, especially in the lungs.
  • Test results (such as IgE or CRP) can change without symptoms changing.
  • Doctors make decisions based on the overall pattern over time, not a single test result.

Table of contents

What is inflammation and why does it matter?

Inflammation is the body’s way of responding to something it sees as harmful. In aspergillosis, this is usually the fungus Aspergillus.

This response involves immune cells, chemicals, and changes in the lungs that aim to control the fungus. However, if inflammation continues over a long period (chronic inflammation), it can also contribute to:

  • Ongoing symptoms (cough, breathlessness, fatigue)
  • Mucus production
  • Damage to lung tissue over time

Important: inflammation can be present at a low level without causing active damage. This is common in chronic conditions.

Inflammation in different types of aspergillosis

The type of inflammation depends on the form of aspergillosis:

  • Allergic Bronchopulmonary Aspergillosis (ABPA): driven by an overactive allergic response. Blood markers such as IgE and eosinophils are often used to monitor this.
  • Chronic Pulmonary Aspergillosis (CPA): caused by long-term infection in damaged lung tissue, leading to ongoing inflammation and structural changes.
  • Aspergillus bronchitis: persistent infection with inflammation, often causing chronic cough and sputum.

In all cases, inflammation may improve with treatment but often does not disappear completely.

Clear definitions: disease states

Doctors use the following terms to describe how the disease is behaving:

  • Active disease: symptoms, tests, or scans are getting worse over time
  • Flare-up: a short-term worsening, often triggered by infection or another stress on the body
  • Stable: no clear overall change over time
  • Improving / responding to treatment: symptoms and/or tests are getting better
  • Remission: minimal or no signs of active disease (used more often in ABPA)

Key point: these states are not fixed — patients may move between them.

What does “stable disease” mean in practice?

“Stable” means that, over a period of time (weeks to months), there is no clear evidence that the disease is progressing.

This usually includes:

  • No worsening of key symptoms
  • No new complications (e.g. haemoptysis, significant weight loss)
  • Imaging (CT scans) showing no progression
  • No need to increase treatment

What stable does NOT mean:

  • It does not mean symptoms are absent
  • It does not mean inflammation is zero
  • It does not mean you will feel the same every day

Many patients with stable disease still experience day-to-day variation in symptoms.

Why other infections cause flare-ups

People with aspergillosis are more vulnerable to other lung infections (bacterial or viral).

This is because:

  • Lung structure may already be damaged
  • Mucus clearance is less effective
  • The immune system is already active

When another infection occurs, it can trigger a flare-up, causing:

  • Increased cough and breathlessness
  • More or thicker sputum
  • Fatigue and feeling unwell
  • Raised inflammatory markers (e.g. CRP)

Crucial point: this does not necessarily mean the aspergillosis itself is worsening. It is often a temporary additional problem.

Understanding test results

Doctors use several types of tests to monitor inflammation and disease activity:

  • CRP / ESR: general markers of inflammation
  • IgE: particularly important in ABPA
  • Eosinophils: linked to allergic inflammation
  • CT scans: show structural changes in the lungs
  • Sputum cultures: detect infection

Important limitations:

  • No single test gives a complete picture
  • Results can fluctuate for many reasons
  • Changes must be interpreted over time

When test results worsen but symptoms do not

This situation is common, especially in ABPA.

For example, IgE levels may rise without any noticeable change in symptoms.

This may happen because of:

  • Natural biological variation
  • Exposure to allergens
  • A mild or early flare that has not yet caused symptoms

Key point: a change in a single test result does not automatically mean the disease is worsening.

Doctors will usually:

  • Repeat tests
  • Look for consistent trends
  • Assess symptoms and scans

If symptoms remain stable and no other changes are seen, the condition may still be considered stable — but monitored more closely.

How doctors decide what is happening

Clinicians do not rely on a single result. Instead, they assess the pattern over time:

  • Are symptoms changing?
  • Are test results consistently rising or falling?
  • Are scans stable or changing?
  • Is the patient responding to treatment?

This combined assessment is called the clinical picture.

Common questions

If I feel better, what is that called?

This is usually described as improving or responding to treatment. In some cases (especially ABPA), it may be called remission.

Does inflammation always mean damage?

No. Low-level inflammation can persist without causing further harm.

Why do my symptoms change from day to day?

This is common and often relates to infections, environment, or general health rather than disease progression.

Can aspergillosis affect the whole body?

It can have wider effects, but it mainly affects the lungs in most patients.

When to seek medical advice

Seek medical advice if you notice:

  • Persistent worsening of symptoms
  • New haemoptysis (coughing up blood)
  • Significant weight loss
  • Symptoms not improving after a suspected infection
  • Concerns about test results

Author and review

Author: Aspergillosis Patient Education Team
Reviewed by: National Aspergillosis Centre (UK)

References

  • Denning DW et al. Chronic pulmonary aspergillosis guidelines
  • ISHAM ABPA guidelines

This article is for general information only and is not a substitute for medical advice.

by GAtherton

AntifungalInteractions.org – A Specialist Resource for Safer Antifungal Treatment

Last reviewed: April 2026

Managing antifungal medications can be complex. Many antifungal drugs interact with other medicines, foods, and even supplements.
To support both patients and healthcare professionals, a dedicated resource is available:
AntifungalInteractions.org.

Key Points

  • A specialist database focused specifically on antifungal drug interactions
  • More detailed and targeted than general resources such as the British National Formulary (BNF)
  • Includes guidance designed for both healthcare professionals and patients
  • Regularly updated (typically several times per month)
  • Maintained by an experienced clinical pharmacist and prescriber
  • Owned and supported by the Fungal Infection Trust

What is AntifungalInteractions.org?

AntifungalInteractions.org is a dedicated online database designed to help users understand how antifungal medications interact with:

  • Other prescribed drugs
  • Over-the-counter medications
  • Herbal supplements
  • Certain foods and drinks

Unlike general drug reference tools, this resource focuses specifically on antifungal medicines, making it particularly useful for conditions such as aspergillosis, where treatment often involves long-term or complex therapy.

Why This Resource Matters

1. Antifungal drugs are complex

Common antifungal medications such as azoles (e.g. itraconazole, voriconazole, posaconazole) are known to interact with many other drugs.
These interactions can:

  • Increase side effects
  • Reduce treatment effectiveness
  • Require dose adjustments or monitoring

2. General resources may not go far enough

Widely used tools like the British National Formulary (BNF) are essential, but they are designed for broad use across all medicines.
AntifungalInteractions.org provides:

  • More detailed interaction explanations
  • Practical interpretation of risk
  • Condition-specific relevance

3. It supports informed discussions

The database is not a replacement for clinical advice, but it can help patients and clinicians:

  • Prepare for consultations
  • Understand potential risks
  • Ask more informed questions

Who Maintains the Database?

AntifungalInteractions.org is maintained by:

Saarah Niazi-Ali
MPharm, PG Cert (General Pharmacy Practice), PG Dip (Advanced Clinical Pharmacy Practice),
Independent Pharmacist Prescriber, Non-Medical Prescribing (Level 7), Final Medical Signatory

The database is updated frequently—typically 3–4 times per month, often on a weekly basis—ensuring that information remains current and clinically relevant.

Governance and Ownership

The resource is owned and supported by the Fungal Infection Trust, a UK-based organisation dedicated to improving the understanding, diagnosis, and treatment of fungal diseases.

This ensures that the database:

  • Remains focused on patient benefit
  • Is aligned with specialist fungal disease care
  • Supports both clinical practice and patient education

Who Is It For?

Patients and carers

  • To better understand their medications
  • To check for potential interactions
  • To support conversations with their clinical team

Healthcare professionals

  • Infectious disease specialists
  • Respiratory clinicians
  • Pharmacists
  • GPs managing complex patients

It is particularly valuable for clinicians managing conditions such as:

  • Chronic pulmonary aspergillosis (CPA)
  • Allergic bronchopulmonary aspergillosis (ABPA)
  • Other fungal infections requiring long-term antifungal therapy

How Does It Compare to Other Resources?

Feature AntifungalInteractions.org General Drug References (e.g. BNF)
Focus Antifungal-specific All medicines
Level of detail High (specialist) Moderate (broad coverage)
Patient-friendly explanations Yes Limited
Update frequency Frequent (monthly/weekly) Regular but broader scope

Important Notes for Patients

While this database is a valuable resource, it should be used appropriately:

  • Do not stop or change medication based on what you read
  • Always discuss concerns with your doctor, pharmacist, or specialist team
  • Use the information to support—not replace—medical advice

When to Seek Medical Advice

Contact your healthcare provider if you:

  • Start a new medication while on antifungal treatment
  • Experience new or worsening side effects
  • Are unsure whether a supplement or food is safe
  • Have been advised of a potential interaction

Summary

AntifungalInteractions.org is a highly valuable, specialist resource that fills an important gap in antifungal care.
Its combination of:

  • Expert clinical oversight
  • Frequent updates
  • Patient-accessible explanations
  • Specialist focus

makes it an important tool for both patients and healthcare professionals managing fungal disease.

Further Reading

Author & Review

Prepared for Aspergillosis patient and healthcare education.
Content aligned with UK specialist practice and reviewed for clarity and safety.

by GAtherton

Voriconazole interactions: what patients need to know

Last reviewed: April 2026

Key points

  • Voriconazole interacts with many medicines.
  • It affects several liver enzyme pathways, including CYP3A4, CYP2C19, and CYP2C9.
  • Its behaviour can vary more from one person to another than some other azoles.
  • Some medicines can make voriconazole stronger, while others can make it less effective.
  • Visual side effects and sensitivity to sunlight are well recognised with voriconazole.

What is voriconazole?

Voriconazole is an azole antifungal often used in serious fungal infections, including aspergillosis. It can be very effective, but it also has a relatively complex interaction profile.

Why voriconazole interacts with so many medicines

Voriconazole affects several liver enzyme systems, including CYP3A4, CYP2C19, and CYP2C9. It can increase the levels of some medicines, while some other medicines can lower voriconazole levels and reduce its effectiveness.

Because voriconazole metabolism varies between patients, the same combination can affect people differently.

The interaction groups most likely to matter

Steroids

Voriconazole can increase exposure to some steroids, including inhaled steroids, which may increase the risk of steroid side effects.

Medicines that reduce voriconazole levels

Some medicines, including certain anti-seizure medicines and rifampicin-type antibiotics, can reduce voriconazole levels so much that the antifungal may not work properly.

Blood thinners

Some blood thinners may become stronger when taken with voriconazole, increasing bleeding risk.

Heart rhythm medicines

Voriconazole can contribute to QT prolongation, so combinations with other medicines that affect heart rhythm may be particularly important.

Statins

Some statins can become stronger when taken with voriconazole, increasing the risk of muscle side effects.

Immunosuppressants

Medicines such as tacrolimus and ciclosporin can rise significantly with voriconazole and often require specialist monitoring and dose adjustment.

Sedatives and some mental health medicines

Some sedatives and psychiatric medicines can become stronger when combined with voriconazole, increasing the risk of drowsiness, confusion, or other side effects.

Voriconazole-specific issues patients should know

Visual changes

Temporary visual disturbances are well recognised with voriconazole. Patients may notice blurred vision, brighter vision, or changes in colour perception.

Photosensitivity

Voriconazole can increase sensitivity to sunlight. Patients should use sensible sun protection and report new skin changes, especially during long-term treatment.

Variable drug levels

Voriconazole levels can vary between patients, which is one reason some teams use therapeutic drug monitoring in selected situations.

What patients should do in practice

  • Tell your clinical team and pharmacist that you are taking voriconazole.
  • Check before starting new medicines, including over-the-counter or herbal products.
  • Report visual changes, significant sensitivity to sunlight, or a change in symptoms after a medicine change.
  • Do not change treatment without advice.

When to seek medical advice

Seek medical advice urgently for severe bleeding, fainting, severe palpitations, marked confusion, or rapid worsening after a medicine change.

Important

This page is educational and does not list every interaction. For a full check, use the BNF interaction checker or speak to a pharmacist or clinician.

References

by GAtherton

Itraconazole interactions: what patients need to know

Last reviewed: April 2026

Key points

  • Itraconazole can interact with many other medicines.
  • It usually does this by affecting liver enzymes, especially CYP3A4.
  • Some combinations need careful monitoring, while others are best avoided.
  • Capsules and liquid formulations are not handled by the body in exactly the same way.
  • This page highlights the interactions most likely to matter to people with aspergillosis.

What is itraconazole?

Itraconazole is an azole antifungal used in aspergillosis and other fungal infections. It has a relatively high interaction burden, so medicine checks are especially important before starting it and whenever another medicine is added, stopped, or changed.

Why itraconazole interacts with so many medicines

Itraconazole can increase the levels of some other medicines by affecting liver enzymes, especially CYP3A4. This means that some medicines may become stronger than intended, which can increase the risk of side effects or toxicity.

The interaction groups most likely to matter

Steroids and inhalers

This is one of the most important groups for many aspergillosis patients, especially those with asthma or allergic bronchopulmonary aspergillosis. Itraconazole can increase exposure to some steroids, including inhaled steroids, which may increase the risk of steroid side effects.

Possible symptoms to report: unusual weight gain, easy bruising, increased facial rounding, mood changes, worsening blood sugar control, weakness, or marked fatigue.

Statins

Some statins can become much stronger when taken with itraconazole. This can increase the risk of muscle toxicity.

Possible symptoms to report: new muscle pain, muscle weakness, or dark urine.

Blood thinners

Itraconazole can increase the effect of some blood thinners, which may raise bleeding risk.

Possible symptoms to report: unusual bruising, bleeding that is hard to stop, black stools, vomiting blood, or coughing up much more blood than usual.

Heart and rhythm medicines

Some combinations can increase the risk of serious heart rhythm problems. Itraconazole is also used cautiously in people with a history of ventricular dysfunction or heart failure unless the infection is serious.

Possible symptoms to report: fainting, palpitations, marked dizziness, increasing ankle swelling, or worsening breathlessness.

Sleeping tablets, sedatives, and some mental health medicines

Some sedatives and psychotropic medicines can become stronger when combined with itraconazole, increasing the risk of drowsiness, confusion, falls, or breathing problems.

Immunosuppressants

Medicines such as tacrolimus and ciclosporin can rise significantly when taken with itraconazole and usually need specialist monitoring.

Medicines that can make itraconazole less effective

Some medicines lower itraconazole levels, which means the antifungal may not work as well. This can happen with some anti-seizure medicines, rifampicin-type antibiotics, and some antiviral medicines.

Acid-reducing medicines and itraconazole capsules

Reduced stomach acid can lower the absorption of itraconazole capsules. This means reflux medicines, antacids, and some acid-suppressing treatments can affect how well the capsules work. The liquid formulation behaves differently and should not be treated as interchangeable with capsules.

What patients should do in practice

  • Keep a current medicines list and bring it to appointments.
  • Tell clinicians and pharmacists if you are taking itraconazole.
  • Ask specifically about inhalers, steroid tablets, statins, blood thinners, and reflux treatment.
  • Do not change doses or stop medicines without advice.
  • If your itraconazole formulation changes, ask whether it should be taken with food or on an empty stomach.

When to seek medical advice

Seek urgent medical advice for severe bleeding, black stools, vomiting blood, severe muscle pain, fainting, marked palpitations, or rapidly worsening breathlessness.

Important

This page is not a full interaction database. For a complete medicine-by-medicine check, use the BNF interaction checker or speak to a pharmacist or clinician.

References

by GAtherton

Amphotericin B interactions: what patients need to know

Last reviewed: April 2026

Key points

  • Amphotericin B comes in different formulations, and they are not interchangeable.
  • Its main interaction risks are different from the azoles.
  • The most important problems are usually kidney stress, low potassium, low magnesium, and additive toxicity with other medicines.
  • These risks matter most with intravenous treatment.
  • If you hear “amphotericin B”, it is important to know which formulation is being used.

What is amphotericin B?

Amphotericin B is an antifungal used mainly for serious fungal infections. In modern UK practice this often means liposomal amphotericin B, but conventional amphotericin B deoxycholate is also a recognised formulation.

Why amphotericin B interactions are different from azoles

Unlike azole antifungals, amphotericin B does not mainly cause medicine interactions through liver enzymes. Its most important interaction risks usually relate to kidney injury, low potassium, low magnesium, and infusion-related effects.

The interaction groups most likely to matter

Other medicines that can damage the kidneys

This is one of the most important groups. Combining amphotericin B with other nephrotoxic medicines can increase the risk of kidney injury.

Diuretics, steroids, and other medicines that lower potassium

Amphotericin B can lower potassium, and some other medicines can make this worse. This may increase the risk of weakness, cramps, or heart rhythm problems.

Digoxin and heart-rhythm-sensitive situations

Low potassium caused by amphotericin B can make digoxin-related toxicity more likely and may increase the importance of electrolyte monitoring.

Flucytosine

When combined with flucytosine, specialist monitoring may be needed because toxicity can increase.

Some cancer medicines and intensive hospital treatments

In hospital, additive toxicity with other intensive treatments may be particularly important, especially where kidneys and electrolytes are already under strain.

White blood cell transfusions

Acute lung reactions are a recognised specialist concern if amphotericin B is given during or soon after leukocyte transfusions.

Why the formulations matter

Amphotericin B formulations are not interchangeable. Conventional amphotericin B deoxycholate and liposomal amphotericin B have different dosing, different handling by the body, and different safety profiles. Using the wrong formulation in the wrong dose has caused serious and even fatal errors.

In general, liposomal amphotericin B is less nephrotoxic than conventional amphotericin B deoxycholate, but it still requires careful monitoring.

What patients should do in practice

  • Ask which amphotericin B formulation is being used.
  • Tell the clinical team about all medicines, especially kidney-risk medicines, diuretics, steroids, and digoxin.
  • Expect blood tests to monitor kidney function, potassium, and magnesium during intravenous treatment.
  • Report weakness, reduced urine output, worsening swelling, palpitations, or marked dizziness.

When to seek medical advice

Seek urgent medical help for severe breathlessness, fainting, major palpitations, or a rapid deterioration during treatment.

Important

This page is educational and does not list every possible interaction. Amphotericin B treatment is usually managed by specialist teams, especially when given intravenously.

References

by GAtherton

Isavuconazole interactions: what patients need to know

Last reviewed: April 2026

Key points

  • Isavuconazole can interact with other medicines, but its interaction profile is often less complex than older azoles.
  • It mainly interacts through CYP3A4.
  • Some medicines can increase isavuconazole levels, while others can reduce its effectiveness.
  • It has an important difference from some other azoles: it can shorten the QT interval.
  • It is still essential to check new medicines carefully.

What is isavuconazole?

Isavuconazole is a newer azole antifungal used in invasive aspergillosis and some other serious fungal infections. It is often seen as having a more predictable interaction profile than some older azoles, but it still has important interactions.

Why isavuconazole interacts with other medicines

Isavuconazole is mainly linked to CYP3A4. This means some medicines can become stronger when combined with it, while other medicines can lower isavuconazole levels and reduce its effectiveness.

The interaction groups most likely to matter

Medicines that reduce isavuconazole effectiveness

Some medicines, including rifampicin-type antibiotics and certain anti-seizure drugs, can lower isavuconazole levels and may make treatment ineffective.

Steroids

Some steroid levels may rise with isavuconazole, although the interaction pattern is often less intense than with some older azoles.

Immunosuppressants

Medicines such as tacrolimus and ciclosporin may increase and usually need specialist review and monitoring.

Blood thinners

Some blood thinners may become stronger, increasing bleeding risk.

Statins

Some statin levels may increase, which can raise the risk of muscle side effects.

Important isavuconazole-specific points

QT shortening

Unlike several other azole antifungals, isavuconazole can shorten the QT interval. This is an important difference and should be considered when other heart medicines are being reviewed.

Generally simpler interaction profile

Compared with itraconazole and voriconazole, isavuconazole is often considered a little easier to manage in patients taking several medicines, although checks are still essential.

What patients should do in practice

  • Tell your pharmacist or clinician if you are taking isavuconazole.
  • Check before starting prescription, over-the-counter, or herbal medicines.
  • Ask specifically about anti-seizure drugs, antibiotics, blood thinners, and heart medicines.
  • Do not stop or change medicines without advice.

When to seek medical advice

Seek medical advice urgently for severe bleeding, fainting, severe palpitations, severe muscle pain, or rapid worsening after a medicine change.

Important

This page is educational and not a complete interaction database. For a full check, use the BNF interaction checker or speak to a pharmacist or clinician.

References

by GAtherton

Posaconazole interactions: what patients need to know

Last reviewed: April 2026

Key points

  • Posaconazole can interact with other medicines, although its interaction pattern is often a little simpler than itraconazole or voriconazole.
  • It mainly interacts through CYP3A4 inhibition.
  • Important interaction groups include immunosuppressants, steroids, blood thinners, and some heart medicines.
  • Some medicines can reduce posaconazole levels and make treatment less effective.
  • Tablets and oral suspension are not interchangeable in the same way.

What is posaconazole?

Posaconazole is an azole antifungal used in aspergillosis and in some high-risk patients for prevention of fungal infection. It is often seen as somewhat easier to manage than some older azoles, but important interactions still exist.

Why posaconazole interacts with other medicines

Posaconazole mainly affects CYP3A4, a key liver enzyme involved in handling many medicines. This means some drugs can become stronger, while some combinations can lower posaconazole levels and make it less effective.

The interaction groups most likely to matter

Steroids

Posaconazole can increase exposure to some steroids, including inhaled or oral steroids, which may increase the risk of steroid side effects.

Immunosuppressants

Medicines such as tacrolimus and ciclosporin can rise significantly with posaconazole and usually need close specialist monitoring.

Blood thinners

Some blood thinners may become stronger, increasing bleeding risk.

Statins

Some statins can rise in level, increasing the risk of muscle problems.

Heart rhythm medicines

Some combinations can increase the risk of heart rhythm problems and need careful review.

Medicines that reduce posaconazole effectiveness

Some medicines, including rifampicin-type antibiotics and certain anti-seizure drugs, can lower posaconazole levels and may make treatment less effective.

Posaconazole formulations and absorption

Posaconazole comes in different forms, including tablets, oral suspension, and infusion. The oral suspension and tablets are not handled identically by the body and should not be assumed to be interchangeable dose-for-dose without clinical advice.

In practice, the tablets tend to be more predictable than the suspension.

What patients should do in practice

  • Tell your pharmacist or clinician if you are taking posaconazole.
  • Ask about new medicines, especially blood thinners, steroids, statins, and heart medicines.
  • If your formulation changes, ask whether there are any special instructions.
  • Do not stop or swap medicines without advice.

When to seek medical advice

Seek medical advice urgently for severe bleeding, fainting, major palpitations, severe muscle pain, or rapid worsening after a medicine change.

Important

This page does not list every interaction. For a full check, use the BNF interaction checker or speak to a pharmacist or clinician.

References

by GAtherton

Antifungal drug interactions: what patients with aspergillosis need to know

Last reviewed: April 2026

Key points

  • Antifungal medicines can interact with other medicines, including inhalers, steroid tablets, blood thinners, heart medicines, cholesterol tablets, and some over-the-counter or herbal products.
  • The azole antifungals usually interact by affecting how the liver handles medicines.
  • Amphotericin B is different: its main interaction risks are more often linked to kidneys, potassium, magnesium, and infusion-related effects.
  • This page gives an overview. It does not list every interaction.
  • For a full medicine-by-medicine check, use the BNF interaction checker or ask a pharmacist or clinician.

Why interactions matter in aspergillosis

People with aspergillosis often take more than one medicine. This may include inhalers, steroid tablets, medicines for reflux, antibiotics, pain relief, blood pressure treatment, blood thinners, cholesterol tablets, and drugs for other long-term conditions. That means medicine checks are especially important whenever an antifungal is started, stopped, or changed.

How the main antifungals differ

Most long-term interaction questions in aspergillosis involve the azole antifungals: itraconazole, voriconazole, posaconazole, and isavuconazole. These mainly interact because they affect liver enzymes, especially CYP3A4, although some also affect CYP2C9 and CYP2C19.

Amphotericin B behaves differently. Its most important risks are usually kidney stress, low potassium, low magnesium, and additive toxicity with other medicines rather than classic liver-enzyme interactions.

Quick comparison table

Antifungal Main interaction pattern Typical complexity Important extra point
Itraconazole Strong enzyme-based interactions, especially CYP3A4 High Capsules and liquid are not handled by the body in the same way
Voriconazole Complex enzyme-based interactions involving several CYP pathways High More variable between patients; visual side effects and photosensitivity are well recognised
Posaconazole Mainly CYP3A4-related interactions Moderate Tablets and oral suspension are not interchangeable in the same way
Isavuconazole Mainly CYP3A4-related interactions, usually less complex than older azoles Lower to moderate Can shorten the QT interval
Amphotericin B Kidney, potassium, magnesium, and infusion-related interaction risks Different rather than simpler Formulations are not interchangeable

Individual antifungal guides

What patients should do in practice

  • Keep an up-to-date list of all medicines, including inhalers, creams, over-the-counter medicines, supplements, and herbal products.
  • Tell your doctor, nurse, pharmacist, or hospital team that you are taking an antifungal.
  • Do not start, stop, or swap medicines on your own because of something you have read online.
  • Ask specifically about new medicines, steroid changes, reflux treatment, blood thinners, cholesterol medicines, and heart medicines.

When to seek medical advice

Seek medical advice promptly if symptoms change after a medicine is started, stopped, or changed. Seek urgent help for severe bleeding, fainting, severe muscle pain, marked palpitations, rapidly worsening breathlessness, severe drowsiness, or a sudden significant decline in your health.

Important

This resource is educational. It does not replace personalised advice from your clinical team, GP, or pharmacist, and it is not a complete interaction database.

References

by GAtherton