When should you see a doctor about unexplained fever?

Fever is a body response that can accompany infection, inflammation, medicines, or other illness. In oncology, fever may also occur with leukaemia, lymphoma, or a treatment-related reduction in infection-fighting cells. Acute leukaemias can present with fever, and childhood cancer has varied warning signs. Fever alone does not identify cancer, and the temperature pattern, examination, and other symptoms guide the assessment.

Check your temperature with the same reliable method and write down readings, timing, chills, medicines, recent travel, sick contacts, and other symptoms. Drink fluids if you can and follow the instructions given by your clinician. Do not start leftover antibiotics. Tell the healthcare service if you have cancer, recently received treatment, or take medicines that affect immunity.

Seek urgent help for fever with confusion, difficulty breathing, a stiff neck, severe headache, fainting, dehydration, a widespread rash, or rapidly worsening illness. Anyone receiving chemotherapy or with known low neutrophils should contact their oncology team immediately about a fever, because febrile neutropenia can require prompt treatment.

Ask what tests may find the cause, whether your medicines or immune system change the response, how to monitor your temperature, and which number or symptom requires immediate contact.