Anti-infective
Azole antifungals
e.g. fluconazole, itraconazole — Common antifungal drugs — effective, but major sources of drug interactions.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Azole antifungals treat fungal infections ranging from thrush and skin infections to serious systemic disease. They come as topical, oral and intravenous forms.
How it works
They block an enzyme fungi need to make ergosterol, an essential part of the fungal cell membrane, weakening and killing the fungus.
In practice
In practice the headline issue with azoles is interactions: they inhibit liver enzymes (especially CYP3A4) and can sharply raise the levels of many other drugs — including some statins, certain anticoagulants and others — so always screen the medication list before prescribing. They can also prolong the QT interval, and the systemic azoles need attention to liver function. Topical use carries far less of this risk than systemic courses.
Examples
Practical use
How to take it & use it well
- Follow the specific instructions for your medicine, as some are taken with food to aid absorption while others are not.
- For longer courses, try to take your dose at the same time each day to keep levels steady.
- Complete the full course even after symptoms improve, as fungal infections can return if treatment stops early.
- Tell any prescriber or pharmacist you are taking an azole, because these medicines interact with many other drugs.
- Report yellowing of the skin or eyes, dark urine, persistent nausea or unusual tiredness, as these can signal a liver problem.
Common uses
- Candidal (thrush) and skin/nail fungal infections
- Serious systemic fungal infections (specialist use)
- Prophylaxis in some immunocompromised patients
Monitoring
- Interacting medicines before and during treatment
- Liver function with systemic courses
- QT where risk factors exist
Weighing it up
Advantages & disadvantages
Advantages
- They treat a wide range of fungal infections, from thrush to more serious internal infections.
- Many can be taken by mouth, allowing treatment at home rather than in hospital.
- Single-dose or short courses are effective for some common infections such as vaginal thrush.
- They are a well-established option with decades of clinical experience behind them.
Disadvantages
- They can affect the liver, so blood tests are sometimes needed during longer treatment.
- They interact with a very large number of other medicines, which can limit their use.
- Some, such as itraconazole, are avoided in people with certain heart problems.
- Absorption of some azoles is unreliable and can be reduced by stomach acid-lowering medicines.
Key safety principles
What to watch for
- Major drug interactions via liver-enzyme inhibition — raise levels of many drugs (check before prescribing).
- QT prolongation with several agents.
- Hepatotoxicity with systemic use; some are avoided in pregnancy.
Key interactions
What to avoid or check alongside
- They raise levels of many statins, increasing the risk of muscle damage, so some statins must be paused or avoided.
- They can increase the effect of warfarin and raise bleeding risk, meaning clotting may need closer checks.
- Combined with certain sedatives such as midazolam, they prolong drowsiness and sedation.
- Acid-lowering medicines such as proton pump inhibitors can cut the absorption of some azoles like itraconazole.
- They can increase levels of some heart-rhythm and blood pressure medicines, raising the chance of side effects.
Patient & carer advice
- Tell us every medicine you take, including over-the-counter and herbal ones
- Report yellowing of the skin or eyes, or dark urine
- Complete the course as advised
Use with
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Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
Azole antifungals: frequently asked questions
What infections do azole antifungals treat?
They treat fungal infections ranging from thrush and skin or nail infections to more serious internal fungal infections, depending on which azole is used.
Why do azoles interact with so many medicines?
They block liver enzymes that break down many drugs, so levels of those other medicines can rise. Always share your full medicine list with your prescriber.
Do I need blood tests on an azole?
For longer courses your prescriber may check your liver with blood tests. Short courses, such as a single dose for thrush, usually do not need monitoring.
Can I drink alcohol while taking an azole?
Occasional light drinking is usually fine, but because these medicines can affect the liver it is sensible to avoid heavy drinking during treatment.
Are azole antifungals safe in pregnancy?
Some are avoided, especially at higher or repeated doses, because of possible risks to the baby. Tell your prescriber if you are or might be pregnant before starting.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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