Why does influenza cause fever?

The temperature centre in the brain responds to immune messengers, which can lead to feeling cold or shivery while the body works toward the new set point. As that response changes, sweating may follow. Fever is a very common presentation of Influenza. Fever also has many causes, so a temperature reading cannot by itself tell you which illness is responsible.

Sip fluids regularly, rest, and use light clothing or bedding that you can adjust as you feel hotter or cooler. Do not force food, but choose small, easy-to-tolerate meals if hungry. If you consider fever medicine, use it only as directed and ask a pharmacist or clinician about suitability when pregnancy, chronic illness, allergies, or other medicines are relevant.

Seek emergency care for breathing difficulty, chest pain, confusion, a seizure, severe neck stiffness, a widespread purple-looking rash, or inability to stay awake. Contact a clinician if fever is accompanied by worsening symptoms, clear dehydration, persistent vomiting, or if you are at higher risk from influenza because of pregnancy, immune suppression, or a significant health condition.

Ask what symptoms should trigger a same-day review and whether you need testing or treatment based on your circumstances. Tell the clinician how you measured your temperature, when it began, what medicines you have taken, and whether you have cough, breathlessness, rash, or urinary symptoms.