What should you know about viral pyrexia?

Fever is part of the body's response to infection. A viral illness may also cause tiredness, chills, sweating, headache, aches, cough, a runny nose, sore throat, vomiting or diarrhoea. The pattern depends on the virus and the person's age and health. A fever alone cannot identify the virus or prove that the illness is harmless.

A common cold, influenza, COVID-19, chickenpox and croup can all include fever. Acute bronchitis and bronchiolitis may also begin with viral symptoms. Bacterial illnesses, heat exposure, medicines and inflammatory conditions can cause a high temperature too, so the wider picture matters.

Drink regularly, choosing small frequent sips if nausea is present. Rest, wear light clothing and keep the room comfortably ventilated. Check how the person is behaving and drinking rather than focusing only on the thermometer reading. Fever-reducing medicine may ease discomfort; use it only as directed on the label or by a clinician, and check before giving it to a child or combining products.

Avoid cold baths, alcohol rubs and wrapping up heavily. Stay home while unwell and wash hands often. Do not start antibiotics unless a clinician has identified a bacterial infection; antibiotics do not treat viruses.

Seek urgent help for trouble breathing, blue or grey lips, a seizure, a stiff neck, a rapidly spreading purple or non-blanching rash, severe confusion, unusual difficulty waking, or inability to keep fluids down. A baby with a fever, a person with a weakened immune system, or someone who is pregnant may need prompt individual advice.

Arrange medical review if the fever is worsening, keeps returning, lasts longer than expected for the illness, or comes with severe localised pain, dehydration, or a marked change in alertness. Take a list of medicines and note the temperature pattern and other symptoms.

Could this fever fit a viral illness, or do I need testing? Which fever medicine is suitable with my health conditions and current medicines? What changes should prompt same-day assessment? When can I return to work, school or usual activities?