Understanding Antifungal Monitoring in Aspergillosis Treatment
If you’re taking posaconazole to treat Aspergillus-related conditions like ABPA (Allergic Bronchopulmonary Aspergillosis) or CPA (Chronic Pulmonary Aspergillosis), your doctor may ask for blood tests to check if the drug is reaching the right levels in your body.
Sometimes, those tests come back showing “undetectable” or “very low” levels, even when you’ve been taking the medication exactly as prescribed.
This can be worrying — but there are several common reasons this happens, and it doesn’t always mean the medicine isn’t working or that you’ve done something wrong.
❓ What Is Posaconazole?
Posaconazole is an antifungal medicine used to treat infections caused by the Aspergillus fungus. It comes in tablet, liquid, or IV forms. Most people take the tablet once a day — often for many weeks or months.
To work properly, the drug needs to reach a certain level in your bloodstream. This is why your team may request a blood test to check how well your body is absorbing it.
🔍 Reasons Your Posaconazole Levels May Be Low or Undetectable
1. Not Enough Fat in Your Diet
Posaconazole needs some fat in your meal to be absorbed properly — especially the liquid version.
Try to take it with a meal that includes:
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Dairy (cheese, yoghurt, full-fat milk)
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Eggs, nuts, or oily fish
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A little olive oil or butter in cooking
Tip: Never take it on an empty stomach!
2. Other Medications or Supplements
Some medications and remedies can reduce how well posaconazole is absorbed, including:
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Proton pump inhibitors (e.g. omeprazole, lansoprazole)
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Antacids
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Rifampicin
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Herbal supplements like St John’s Wort
Let your doctor or pharmacist know about everything you take — even vitamins and over-the-counter products.
3. Timing of the Blood Test
The blood test should be taken just before your next dose (called a trough level).
If it’s taken too early (after a fresh dose), or too late (if you missed a dose), it may give a misleading result.
4. Problems with Absorption
Some medical conditions can make it harder for your body to absorb medications, including:
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Coeliac disease
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Crohn’s or colitis
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Chronic diarrhoea or digestive issues
If you have any of these, your doctor may suggest an alternative form — like switching from liquid to tablet or tablet to IV.
5. Lab or Sample Error
Occasionally, there may be a problem with the blood sample — like a delay in handling, or a lab processing issue. In that case, your team may simply repeat the test.
✅ What You Can Do
✔️ Take your medicine with food (especially with fat)
✔️ Tell your team about other medications
✔️ Check which form you’re taking (tablets are usually better absorbed than the liquid)
✔️ Ask when your blood test should be done
✔️ Don’t panic if the result is low — just repeat the test with support from your team
🩺 Why This Matters
Getting the right amount of posaconazole in your body is essential to:
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Help clear fungal infection
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Prevent it from spreading
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Reduce symptoms like coughing, breathlessness, and mucus
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Avoid the risk of fungal resistance
💬 Talk to Your Healthcare Team
If you’re concerned about your levels or not feeling better, don’t stop your medication — contact your team. There may be a simple fix like adjusting your dose, changing the form of medicine, or switching how and when you take it.
📘 For more information
Visit: www.aspergillosis.org
Or speak to your GP, pharmacist, or specialist team.
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