Fever: when to seek urgent care
During leukemia treatment, a fever should not be treated like an ordinary cold. When neutrophils are low, a fever can be the first and sometimes the only signal of a serious infection, and it needs urgent care. This topic explains how to measure your temperature properly, when to call straight away, what happens in hospital and how to prepare in advance.
01Short answer
02Simple explanation
In a healthy person, a fever usually means the body is fighting a germ, and it normally settles with a few days’ rest. During leukemia treatment things are different: when neutrophils are low, an infection can spread very quickly.
When neutrophils are low, the usual signs of infection — redness, swelling, pus — are weak or invisible. That is why a fever is often the only signal. Sometimes you feel only slightly “off”, but even that can be the start of a serious infection.
A serious infection can spread through the whole body and cause sepsis: blood pressure falls and organs work less well. Sepsis can develop within hours, but antibiotics started in time help greatly to prevent it. That is why every minute counts.
The most important rule is simple: fever means call now. Do not wait until the morning, do not “test” it with a fever-reducing medicine, and do not start antibiotics yourself. There is no need to feel embarrassed about calling — hematology teams work around the clock precisely for these calls.
Preparing in advance saves time: a reliable thermometer at home, your team’s number where you can see it, a card with your diagnosis and treatment, and a bag packed for hospital. Your family should know these rules too.
03Scientific explanation
Definition: according to IDSA, febrile neutropenia is a single oral temperature of ≥38.3 °C or ≥38.0 °C sustained over an hour, with an ANC <0.5×10⁹/L (or expected to fall to this level within 48 hours). NICE defines neutropenic sepsis as a temperature >38 °C or signs of sepsis with an ANC ≤0.5×10⁹/L. In practice, patients are usually given a simpler rule: 38 °C or higher — call straight away. In people taking steroids and in older people, infection may occur without a fever.
The “golden hour”: NICE and ESMO guidelines recommend that, when neutropenic sepsis is suspected, empirical intravenous antibiotics start as soon as possible after arrival at hospital, ideally within one hour. A broad-spectrum antipseudomonal beta-lactam is usually used; there is no need to wait for the neutrophil count before starting antibiotics. At the start, blood cultures (from a peripheral vein and from each lumen of any catheter), a blood count, kidney and liver tests, lactate, and where indicated a urine test and chest X-ray are taken.
Risk assessment: the MASCC index (a score ≥21 means low risk) and the CISNE score help decide, for selected patients — usually with solid tumours — whether outpatient (home) treatment with tablets is possible (ASCO/IDSA 2018). People with acute leukemia, after an allogeneic transplant and with prolonged deep neutropenia are usually considered high risk and receive intravenous treatment in hospital.
Next steps: if the fever lasts 3–5 days, doctors may do a CT scan and other tests to look for a fungal infection (for example, aspergillosis) and consider antifungal treatment. If a catheter infection is suspected, the catheter may be removed. How long antibiotics continue and whether they are changed is decided individually, based on culture results, the clinical picture and neutrophil recovery.
04What happens in the body?
Call straight away or call emergency services if:
your temperature is 38 °C or higher (or above the threshold your team gave you); your temperature is below 36 °C; you have shivering, chills or sudden severe weakness; you become confused, drowsy or have trouble speaking; your breathing is fast or difficult; your skin is pale, cold, mottled or bluish; you pass very little urine during the day; there is redness, pain or discharge around a catheter, or shivering starts when the catheter is flushed; you cannot keep medicines down because of vomiting. If there are signs of sepsis, call emergency services directly (103 or 112 in Azerbaijan).
How to take your temperature properly
Use a digital thermometer; if measuring by mouth, wait 15–30 minutes after a hot or cold drink. An armpit reading can be slightly lower. Avoid rectal measurement — during neutropenia and low platelets there is a risk of injury and infection. Do not take fever-reducing medicines (paracetamol and others) before measuring: they can hide a fever. Because of the bleeding risk, do not take medicines such as ibuprofen without agreeing it with your team.
What happens in hospital?
Usually: a quick examination and check for signs of sepsis → blood cultures and blood tests (from the catheter and a vein) → broad-spectrum intravenous antibiotics as soon as possible, ideally within an hour → fluids, oxygen and other support if needed → a urine test, X-ray and other tests → treatment continued or changed according to the results and your condition.
How to introduce yourself at the emergency department
Say straight away: “I am having treatment for leukemia, my last chemotherapy was on …, I may be neutropenic, and I have a fever.” Show your treatment card or hospital letter. If you are left waiting in a queue for a long time, remind the staff again. In many countries, suspected neutropenic sepsis is treated as a priority.
What to prepare in advance
A reliable thermometer; your hematology team’s 24-hour number — in your phone and on the fridge; a card listing your diagnosis, treatment regimen, type of catheter, allergies and current medicines; a packed bag with a charger, medicines, comfortable clothes and toiletries; someone who can take you to hospital at night. Talk this plan through with your family beforehand.
Questions you can ask your doctor
What temperature threshold applies to me? Whom do I call at night, and which hospital should I go to directly? How should I show my treatment card if I have a fever? Which fever and pain medicines are safe for me at home? What should I do with a fever if I take a preventive antibiotic? Which catheter signs are urgent?
05From fever to antibiotics: time matters
With a fever during neutropenia, every step should happen as quickly as possible.
06What to do in different situations
| Situation | What to do | What not to do |
|---|---|---|
| Temperature 38 °C or higher | Call the 24-hour number or go to hospital straight away | Wait until morning, “test” it with a fever-reducing medicine |
| Temperature 37.5–37.9 °C | Follow your team’s threshold; re-check in an hour and call if you get worse | Wait if you feel unwell |
| Below 36 °C, shivering, weakness | Call straight away — this can also be a sign of serious infection | Feel reassured just because there is “no fever” |
| Confusion, fast breathing, mottled skin | Emergency services (103 / 112) | Drive yourself |
| Redness or discharge around a catheter | Call your team the same day; with a fever — straight away | Flush and dress the catheter yourself and wait |
| Fever while taking a preventive antibiotic | Still call straight away | Assume your current medicine is enough |
* This table is general information. Your hematology team sets your thresholds and phone numbers.
07Key terms
- Fever
- A body temperature above normal; during treatment usually 38 °C or higher.
- Febrile neutropenia
- A fever during neutropenia; an emergency.
- Sepsis
- The body’s overwhelming response to infection, with organs starting to fail.
- Neutropenic sepsis
- Sepsis that develops during neutropenia.
- Blood culture
- A test showing whether there are germs in the blood and which antibiotic works on them.
- Empirical antibiotic
- A broad-acting antibiotic started before the germ is known.
- MASCC index
- A scoring system that estimates the risk of complications in febrile neutropenia.
- Lactate
- A substance whose rise in the blood can signal a lack of oxygen in the tissues.
- Hypothermia
- A body temperature below normal; it can also occur with infection.
- Central venous catheter
- A long-term tube in a large vein; it can be a source of infection.
08Key points
- A fever during treatment is a reason to call straight away.
- The usual threshold is 38 °C; follow your team’s threshold.
- A temperature below 36 °C and shivering can also be dangerous.
- Do not take fever-reducing medicines before measuring.
- Avoid rectal thermometers and suppositories.
- Antibiotics should ideally start within one hour.
- Call emergency services if there are signs of sepsis.
- A thermometer, a phone number, a card and a packed bag save time.
09Frequently asked questions
It is midnight, I feel fine, but my temperature is 38.1 °C. Can I wait until morning?
No. During neutropenia an infection can become serious within hours. Call the 24-hour number or go to hospital straight away. Feeling well does not mean the risk is low.
Can I take paracetamol and see whether the temperature comes down?
No. A fever-reducing medicine can hide the fever while the infection continues. Call first; your team will tell you which medicines are safe to take.
I have antibiotics at home. Can I start them myself?
Not unless your team has specifically given you that plan. A fever needs an examination, blood cultures and the right choice of antibiotic. Some teams give selected patients a “start at home” plan, but this is always an individual decision.
Does a fever always mean infection?
Not always. A fever can be a reaction to a blood transfusion, some medicines or the leukemia itself. But during treatment the cause cannot be told apart at home, so every fever is treated as an infection.
My child has a fever. Are the rules the same?
The main rule is the same: a fever in a child on treatment means calling straight away. Children’s hematology teams give their own thresholds and instructions; follow them. Avoid rectal measurement in children too.
I am kept waiting a long time in hospital. What should I do?
When you arrive, say clearly that you are having leukemia treatment and may be neutropenic, and show your treatment card. If the wait drags on, alert the staff again or call your hematology team.
10Questions for your doctor
Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.
At what temperature should I call you immediately?
If I get a fever at night, whom should I call and on which number?
Can I take a fever-reducing medicine on my own when I have a fever?
What should I bring with me if I need to come to hospital?
12Sources
- National Institute for Health and Care Excellence (NICE). Neutropenic sepsis: prevention and management in people with cancer (CG151)
- Annals of Oncology (ESMO), 2016. Management of febrile neutropaenia: ESMO Clinical Practice Guidelines
- Clinical Infectious Diseases (IDSA), 2011. Clinical Practice Guideline for the Use of Antimicrobial Agents in Neutropenic Patients with Cancer: 2010 Update by the Infectious Diseases Society of America
- Journal of Clinical Oncology (ASCO and IDSA), 2018. Outpatient Management of Fever and Neutropenia in Adults Treated for Malignancy: American Society of Clinical Oncology and Infectious Diseases Society of America Clinical Practice Guideline Update
- Journal of Clinical Oncology, 2000. The Multinational Association for Supportive Care in Cancer Risk Index: A Multinational Scoring System for Identifying Low-Risk Febrile Neutropenic Cancer Patients
- StatPearls, NCBI Bookshelf. Febrile Neutropenia
- Cancer Research UK. Sepsis, infection, and cancer
- NHS. Sepsis
- Centers for Disease Control and Prevention (CDC). Information for Patients Who Are Getting Chemotherapy
- Centers for Disease Control and Prevention (CDC). Neutropenia and Risk for Infection
- American Cancer Society. Infections and Cancer
- Blood Cancer UK. Blood cancer and infection
- MedlinePlus (U.S. National Library of Medicine). Low white blood cell count and cancer