Fever and headache: what to know

A common cold, COVID-19 or another infection can produce fever, headache, tiredness and body aches. Dehydration may add a headache, especially after sweating, vomiting or poor fluid intake. Heat exhaustion can cause headache with weakness, heavy sweating and dizziness. Sinus inflammation may cause facial pressure and headache, although allergic rhinitis itself does not usually cause a fever. Dengue fever is another possibility in the right travel or exposure context and may include marked aches, nausea or a rash. These patterns overlap, so symptoms alone cannot confirm a diagnosis.

Rest in a cool, quiet room and drink fluids regularly. Wear light clothing and avoid strenuous activity while feverish. Record when the fever and headache started, any measured temperature, recent travel, insect exposure, sick contacts and medicines taken. Use a fever or pain medicine only as directed on its label and check with a pharmacist if you are pregnant, treating a child, or have liver, kidney or stomach problems.

Seek emergency care for a sudden severe headache, stiff neck, confusion, fainting, seizure, trouble breathing, weakness on one side, new speech or vision problems, or a widespread rash with severe illness. Get same-day medical advice if fluids are difficult to keep down, urination drops, the fever is persistent or worsening, or the headache is new and unusually strong. Mention recent travel to a clinician, particularly if fever is accompanied by bleeding or severe muscle and joint pain.

Ask whether you need an examination or testing, which pain or fever medicine fits your situation, and how to monitor hydration. Share your age, medical conditions, pregnancy status, recent travel and the full list of medicines or supplements.