Fever at night: what it may mean and what to do

Fever at night can happen when an illness is developing, and the pattern alone does not identify its cause. Body temperature naturally varies during the day, while blankets, warm rooms and evening activity can make you feel hotter. Use a thermometer if possible rather than judging by skin warmth alone.

A raised temperature may occur with a respiratory infection such as a common cold, acute bronchitis or COVID-19. Bronchiolitis and croup are respiratory illnesses mainly affecting children. Fever can also accompany a skin infection such as cellulitis, or infections that cause a rash such as chickenpox. Brucellosis is another possible cause in people with relevant animal or unpasteurised dairy exposure. These conditions have different symptoms, so the fever pattern is only one part of the assessment.

Rest, drink fluids regularly, and wear light clothing in a comfortably ventilated room. Check your temperature with the same method each time and record when it rises, along with cough, pain, rash, vomiting or urinary symptoms. Follow the label or a clinician’s instructions before using a fever medicine, and check that another product does not contain the same ingredient. Do not give aspirin to children or teenagers unless a clinician specifically advises it.

Seek urgent help for trouble breathing, confusion, a seizure, severe weakness, a stiff neck, a rapidly spreading rash, or inability to keep fluids down. A baby younger than three months with a measured fever needs prompt medical assessment. Arrange clinical advice if fever keeps returning at night, lasts beyond a short illness, or affects a person who is pregnant, immunocompromised, or living with a serious long-term condition.

Ask whether the temperature and accompanying symptoms fit a respiratory infection, skin infection or another cause; whether you need testing; and which fever medicine is suitable for your age, medicines and health conditions.