Is 37°C a fever?

Body temperature naturally shifts during the day and can vary with activity, sleep, hormones, the environment and the way it is measured. The number should therefore be interpreted alongside symptoms and the measurement method.

A fever is a rise in body temperature that commonly occurs when the immune system responds to an infection or inflammation. A reading from the mouth, ear, armpit or rectum may differ slightly because each site estimates core temperature differently.

Feeling hot, chilled or unwell can still matter even when the thermometer shows 37°C. The temperature may be changing, the device may have been used incorrectly, or another problem may be causing the symptoms without a fever.

Rest for a short while after exercise, a hot bath or being outdoors in strong heat before checking again. Use a clean digital thermometer according to its instructions, measure at the same body site when comparing readings, and note any medicines already taken.

If you otherwise feel well, no fever treatment is needed for 37°C. Drink enough fluid, wear comfortable clothing and monitor how you feel. If symptoms develop, repeat the measurement later rather than relying on a single reading.

Seek urgent medical help for difficulty breathing, severe chest pain, confusion, a seizure, a stiff neck, a rash that does not fade when pressed, blue or grey lips, or marked drowsiness that makes waking difficult, regardless of the thermometer reading.

Contact a clinician promptly if an infant is unwell, if you have a weakened immune system, or if symptoms are worsening or persistent. Signs of dehydration such as very little urine, a very dry mouth or inability to keep fluids down also need assessment.

Tell the clinician where and when the temperature was taken, what device you used, whether readings changed, and which symptoms occurred. Useful questions include whether another measurement method is appropriate, what changes should prompt reassessment, and whether your health conditions or medicines alter the advice.