Fiducia TogetherNeutropenia
Also called Low white blood cell count, Neutropenic sepsis
Too few infection-fighting cells. In someone on chemotherapy, a temperature is a 999-level emergency needing antibiotics within an hour.
Important: This page is general information, not medical advice, and it is not a diagnosis. If you are worried about your health or someone else's, speak to a GP, pharmacist, or call 111. In an emergency, call 999.
What it is
A low count of neutrophils, the white cells that fight bacterial infection.
The commonest cause is chemotherapy, which suppresses the bone marrow, typically with the lowest count around 7 to 14 days after a cycle. It also occurs in leukaemia and myelodysplastic syndrome, with some drugs including carbimazole and clozapine, in severe infection, and in some people harmlessly and permanently, which is common in people of African ancestry and is not a disease.
**Neutropenic sepsis is the emergency.** Without neutrophils, an infection produces few of the usual signs: no pus, minimal redness, sometimes no cough with a chest infection. A temperature may be the only warning, and the person can deteriorate to septic shock within hours.
The standard is antibiotics within one hour of arrival, before any test result. Anybody on chemotherapy is given a 24-hour helpline number and an alert card, and the instruction is to ring it and go straight to hospital, not to a GP and not in the morning.
A temperature of 38C or above, or feeling unwell with a low temperature, or shivering and rigors, all count.
Clozapine and carbimazole both require regular blood monitoring for this reason, and any sore throat or fever on either drug needs an urgent blood count.
Signs you might notice
Fever of 38C or above, or a single reading above 37.5C that persists, or a temperature below 36C.
Shivering, shaking or rigors, with or without a fever.
Feeling generally unwell, flu-like, or just not right.
Sore throat, mouth ulcers, cough, breathlessness, diarrhoea, or burning on passing urine.
Redness or pain around a line or catheter.
Confusion, fast breathing, dizziness or low blood pressure.
**Ring the 24-hour chemotherapy helpline and go straight to hospital.** Do not wait, do not take paracetamol first, because it masks the fever, and do not go to a GP.
Take the alert card. It tells the receiving team to treat within the hour.
For anybody on clozapine or carbimazole, a sore throat or fever needs an urgent blood count the same day.
How it can affect day-to-day life
The instruction people most often break is taking paracetamol for a temperature. It lowers the reading, delays the call, and buys the infection hours.
The card and the number should live in a wallet and be known to everybody in the household, not filed at home.
Precautions between cycles are about sensible avoidance rather than isolation: avoiding people with obvious infections, careful food hygiene, hand washing, and dental care sorted before treatment starts. The specifics change through treatment and should be asked of the team rather than taken from the internet.
Isolation and fear are real costs, and people often withdraw more than is necessary, which harms mood and recovery.
For chronic benign neutropenia, which is normal for the person, the important thing is that it is recorded so that a low count on a routine test does not trigger unnecessary investigation.
Growth factor injections are given to some people to shorten the low period and reduce risk.
Supporting someone well
Know the number, carry the card, and ring at the first sign.
Do not take paracetamol before checking a temperature or before ringing.
Have a working thermometer at home, and check when the person feels off.
Treat shivering without fever as equally serious.
Get dental work done before chemotherapy starts.
Wash hands, handle food safely, and avoid people with obvious infections.
Ask the team what precautions apply to this person now, rather than following generic advice.
For clozapine or carbimazole, get a same-day blood count for any sore throat or fever.
Make sure chronic benign neutropenia is recorded so it is not mistaken for a new problem.
Where to get help
The 24-hour chemotherapy helpline, then straight to the acute oncology or emergency department.
999 for confusion, fast breathing, dizziness or collapse.
Macmillan Cancer Support on 0808 808 00 00.
Blood Cancer UK on 0808 2080 888, and the UK Sepsis Trust for the warning signs.
Tools we make that might help
These are our own products. We have put them here because they do something specific for this condition, not because every page needs a list.
Fiducia Guardian
Temperature readings and the chemotherapy helpline number held with the care record, so a reading of 38 triggers a call rather than a paracetamol.
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Important: This page is general information, not medical advice, and it is not a diagnosis. If you are worried about your health or someone else's, speak to a GP, pharmacist, or call 111. In an emergency, call 999.