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Why antifungal medicine is given during leukaemia treatment | CION Cancer Clinics
Antifungal medicine is given during intensive treatment for acute leukaemia to stop a fungal infection before it starts. Chemotherapy keeps your infection-fighting white cells very low for weeks, and moulds breathed in from the air can take hold. This page explains which medicines are used, when they start and stop, what to watch for, and what only your own haematologist can decide. At CION Cancer Clinics, our haematology team supports patients and families through treatment, cost questions and life at home.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- Why is an antifungal medicine given when there is no fungal infection?
- Which antifungal medicines might you see on the chart?
- When does it start, and when does it stop?
- What side effects and medicine clashes should you know about?
- What do the words on the chart mean?
- What do families often get wrong about antifungal tablets?
- Who may not be given it, and what can this page not tell you?
- Common questions about antifungal cover in leukaemia
The short answer
Why is an antifungal medicine given when there is no fungal infection?
It is given to stop a fungal infection before it starts. Intensive treatment for acute leukaemia wipes out the white cells that normally keep moulds and yeasts in check, and a fungal infection that takes hold in that window is far harder to treat than one that never begins.
Why the risk is so high in acute leukaemia
Fungal spores are in the air everywhere. A healthy person breathes them in and clears them without noticing. The cells that do that clearing are the neutrophils, one type of white cell. Induction chemotherapy for acute myeloid leukaemia, and some phases of treatment for acute lymphoblastic leukaemia, keep those cells very low for a long stretch.
What the medicine is actually doing
The tablet, liquid or drip keeps a steady level of antifungal medicine in your blood through the weeks when your own defences are missing. It is a shield, not a treatment.
Preventive antifungal medicine lowers the risk. It does not remove it, so a fever during low counts still needs urgent attention.On the prescription
Which antifungal medicines might you see on the chart?
The choice depends on the type of leukaemia, the other medicines you are on, your liver and kidneys, and whether you can swallow. Your haematologist sets the medicine and the dose.
Posaconazole
Covers both moulds and yeasts. It is widely used during induction for acute myeloid leukaemia, where mould infections are the main worry.
Your team will watch
- Liver blood tests
- Clashes with other medicines
- Sometimes the level in your blood
Voriconazole or isavuconazole
Also cover moulds. They may be chosen when posaconazole does not suit, or when a scan has raised a question. Voriconazole can cause brief changes in vision and sensitivity to sunlight.
Fluconazole
Covers yeasts such as Candida but not moulds. It may be used where the mould risk is judged lower, for example in some phases of treatment for acute lymphoblastic leukaemia.
Drip options
Micafungin or amphotericin B may be given into a vein when mouth sores or vomiting make tablets impossible, or when tablets clash with an essential leukaemia medicine.
Not sure whether this applies to you?
Ask an oncologistThe course
When does it start, and when does it stop?
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Before or with the first chemotherapy
Most teams start the medicine at the beginning of a treatment block, so the level in your blood is already up before your counts fall.
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Every day through the low-count weeks
You take it daily, including the days you are discharged home. Missed doses let the level drop at exactly the time it matters most.
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Blood level and interaction checks
Some of these medicines are absorbed unevenly, so a blood test may check the level. Every new prescription, including from another doctor, needs to be checked against the antifungal.
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When the counts recover
Your haematologist decides when to stop, usually once your white cells have recovered and stayed up. It may restart with the next block of treatment. Never stop it on your own because you feel well.
Living with it
What side effects and medicine clashes should you know about?
Most people take these medicines without serious trouble. The effects that matter most are the ones you cannot feel, which is why the blood tests continue even when you are well.
What you might notice
Feeling sick, a change in taste, loose motions, headache and skin rash are the common complaints. Voriconazole can make vision look bright or blurred for a short while after a dose, and can make the skin burn easily in the sun, so cover up outdoors. Report yellow eyes, very dark urine or a new rash to the team rather than waiting for the next review.
What the team is checking for
The azole group of antifungals is processed by the liver in the same way as many other medicines. That can push the level of another drug too high. Vincristine, venetoclax, some targeted leukaemia tablets, some heart rhythm medicines and some antibiotics are known examples. Some of these medicines can also affect the heart rhythm, so an ECG may be repeated.
Bring every medicine you take to each visit, including ayurvedic, homeopathic and over-the-counter ones.On your chart
What do the words on the chart mean?
- Mould-active
- An antifungal that works against moulds such as Aspergillus, not only yeasts.
- Azole
- The family name for posaconazole, voriconazole, isavuconazole and fluconazole. Medicines in this family share the same pattern of clashes with other drugs.
- Drug level or TDM
- A blood test measuring how much antifungal is in your blood, to check it is enough to protect you and not so high that it causes harm.
- Absolute neutrophil count (ANC)
- The number of infection-fighting white cells on your blood report. It is the figure your team watches to decide when the risk has passed.
- Galactomannan
- A blood test that looks for a trace of Aspergillus mould.
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Commonly believed
What do families often get wrong about antifungal tablets?
"There is no infection, so the tablet can be skipped."
The whole point is that there is no infection yet. Once a mould has grown in the lungs, treatment is longer, harder on the body and can delay the next block of chemotherapy. Taking the medicine every day is what keeps it working.
"If it is working, a fever cannot be fungal."
Preventive cover lowers the chance of a fungal infection but does not bring it to zero. Any fever during low counts is treated as an emergency, whatever tablets you are on.
"An antifungal from the local pharmacy is the same thing."
Different antifungals cover different fungi, and many clash with leukaemia medicines. Swapping or adding one without your haematologist can leave you unprotected or push another drug to a harmful level.
"Keeping the house spotless means we do not need it."
Cleanliness helps, and avoiding building dust, soil and damp rooms is sensible. But spores are in outdoor air too. Home care works alongside the medicine, never instead of it.
Being straight with you
Who may not be given it, and what can this page not tell you?
Not everyone with a blood cancer needs an antifungal. People on gentler treatment, where white cells do not stay very low for long, often do not get one, because the risk is lower and the medicine carries its own side effects and clashes.
When a different plan is chosen
Someone with significant liver damage, a heart rhythm problem, or an essential leukaemia tablet that clashes badly may be given a different antifungal, a drip instead of a tablet, or closer monitoring instead.
What this page cannot tell you
It cannot tell you which medicine is right for you, how long you will need it, or whether your own dose is correct. Your treatment protocol, blood results and other medicines decide all of that. If something on your prescription does not match what you have read, write the question down and ask the ward team. CION's haematology team reviews each case and can help you understand the plan and what to ask.
Questions we are asked
Common questions about antifungal cover in leukaemia
My father vomited soon after his antifungal tablet. Should he take another?
Do not repeat the dose on your own. Call the ward or the helpline and say which medicine it was and how soon after the dose he vomited. The team may suggest a repeat, an anti-sickness medicine first, or a switch to a drip if vomiting keeps happening. Missing cover repeatedly is worth raising quickly.
Should the tablet be taken with food?
It depends on the medicine and the form. Some are absorbed better with a meal, some should be taken on an empty stomach. Follow the instructions on your own prescription label and ask the pharmacist if they are unclear. Taking it the same way every day helps keep the level steady.
What should we do if a fever starts at home?
Treat any fever during low counts as an emergency. Go to the nearest emergency department the same day, or call 108, and say the person is on leukaemia treatment with low counts. Take the medicine list with you. Do not give paracetamol and wait to see if the temperature settles first.
Why is the antifungal so expensive?
The mould-active medicines cost more than older ones, and the course can run for weeks. Generic versions exist for some. Ask the team whether your scheme or insurance covers it as part of leukaemia treatment. Aarogyasri, CGHS, ECHS and EHS rules change, so check the current position before you buy privately.
Can an antifungal stop the leukaemia treatment working?
It does not act on the leukaemia itself. The concern is the reverse: it can raise the level of some leukaemia medicines, which is why doses are sometimes adjusted by the haematologist. Never change either medicine yourself. Tell the team about every new prescription so the clash can be checked.
Will it damage the liver permanently?
Liver tests often move a little during treatment, and many things besides the antifungal can cause that. Serious lasting damage is uncommon, and regular blood tests are there to catch a problem early. If the tests rise, the team may check the level, change the medicine or watch more closely.
Do children with leukaemia get it too?
Some do, depending on the type of leukaemia, the phase of treatment and the child's age. Children often need a liquid form and a dose set by weight, which the paediatric haematology team works out. Ask how the child should take it if swallowing tablets is hard.
Is there anything we can do at home to lower the risk?
Keep away from building work, dusty rooms, garden soil, compost and damp or mouldy walls. Avoid indoor potted plants near the bed. Wash hands often and keep up mouth care. None of this replaces the medicine, but it cuts down the spores you breathe.
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Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- National Cancer Institute — Infection and cancer treatment
- NHS — Aspergillosis
- Cancer Research UK — Acute myeloid leukaemia (AML)
- Leukaemia & Lymphoma Society — Leukaemia & Lymphoma Society
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Fungal infection during low white cell countsThe symptoms that mean a fungal infection needs checkingWhy cotrimoxazole is given in blood cancerThe other preventive medicine often on the same chartMouth care when white cells are lowEveryday care that lowers infection riskSupportive care in haematologyAll the supportive care guides in one placeLeukaemia guideThe bigger picture of leukaemia and its treatment
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