Understanding Drug Interactions with Antifungal Medications

Information for patients and carers receiving treatment for aspergillosis

Why drug interactions matter

Many antifungal medications used to treat aspergillosis can affect — or be affected by — other medicines you may be taking. These drug interactions can change how well a medication works, increase side effects, or cause unexpected reactions.

Knowing what to watch for and sharing your full medication list with your healthcare team can help keep you safe.

Antifungal medicines that interact with other drugs

Common antifungals:

• Voriconazole
• Posaconazole
• Itraconazole
• Isavuconazole

These drugs are processed through the liver and can interfere with enzymes (like CYP3A4) that control how other medications are broken down.

Examples of drugs that may interact

Heart medications

• Statins (e.g. simvastatin) — can build up and cause muscle damage
• Calcium channel blockers (e.g. amlodipine) — may cause low blood pressure
• Warfarin and other anticoagulants — may require closer INR monitoring

Mental health medications

• SSRIs (e.g. sertraline, fluoxetine) — can increase side effects
• Benzodiazepines (e.g. diazepam) — may be stronger or last longer

Steroids

• Prednisolone — levels may increase with antifungals, increasing risk of side effects

Immunosuppressants

• Tacrolimus, cyclosporine — antifungals can raise their levels significantly

Other

• Oral contraceptives — effectiveness may be reduced (use backup contraception)
• Some diabetes medications — risk of low or high blood sugar
• Antacids or proton pump inhibitors — can reduce absorption of antifungals

What you can do

• Make sure your drug list is kept up to date and brought to every clinic visit or hospital appointment
• You can ask your pharmacist or look up your medicines in the British National Formulary (BNF) or NHS Medicines A-Z to find out more about possible interactions. The Fungal Infection Trust also maintains a list specifically for antifungal medication
• Always give your care team a full, up-to-date medication list, including over-the-counter medicines, supplements, and herbal remedies
• Don’t stop or start any medicines without checking first
• Let your GP and pharmacist know you’re taking antifungal treatment
• Ask your team if your medication needs to be monitored more closely (e.g. blood levels)

Signs of a potential drug interaction

• Unexplained dizziness, fainting, or fast heart rate
• New or worsening side effects
• Signs of toxicity (nausea, confusion, muscle pain, tremors)
• Bleeding or bruising more easily

If you notice anything unusual, contact your healthcare team or pharmacist.