What should you know about the highest fever ever?

Fever is a body response, often to infection, but the number alone cannot identify the cause. A thermometer reading can vary by measurement site and technique, so record the reading, method, and time. Conditions such as acute bronchitis, bronchiolitis, cellulitis, chickenpox, COVID-19, croup, or a common cold can present with fever, but symptoms overlap and examination may be needed.

Children, older adults, pregnant people, and people with weakened immunity can become unwell quickly. A fever that improves and then returns, or one accompanied by a new rash, deserves medical advice.

Rest, take frequent fluids, and use light clothing. Check the temperature with the same reliable method and keep a note of symptoms and medicines. Fever medicines may ease discomfort, but use only a product suitable for the person and follow its label or a clinician's instructions. Do not give aspirin to children unless specifically prescribed.

Seek emergency care for difficulty breathing, blue or grey lips, a seizure, severe drowsiness, confusion, a stiff neck, a non-blanching rash, fainting, or inability to keep fluids down. Infants with a fever need prompt medical advice. Seek same-day review when fever is very high, persistent, worsening, or affecting someone medically vulnerable.

Ask what temperature and symptoms are concerning for your age group, which thermometer method to use, how to manage fluids and medicines, and whether examination or testing is needed to find the cause.