What to know about a 39°C fever

Fever is the body's controlled rise in temperature during illness. Viral and bacterial infections can both cause a 39°C reading, and the temperature by itself cannot identify the cause. Note how the measurement was taken, because oral, ear, underarm, and rectal readings are not directly interchangeable. A person's alertness, breathing, hydration, pain, rash, and other symptoms help determine urgency.

Encourage regular fluids and allow rest in a comfortably cool room. Use light clothing rather than heavy blankets, and avoid cold baths or alcohol rubs. If fever medicine is appropriate, follow the product directions for the person's age and weight, and check the active ingredients to avoid accidental double dosing. Do not give aspirin to a child or teenager with a viral-type illness. Recheck the temperature with the same method and watch the overall condition.

Get emergency help for severe trouble breathing, blue or grey lips, a seizure, marked confusion, difficulty waking, a stiff neck with severe headache, or a rash that does not fade when pressed. Seek prompt clinical advice if the person cannot keep fluids down, passes very little urine, has worsening localised pain, is pregnant or immunocompromised, or the fever persists or returns after improvement. Any fever in a baby younger than three months needs urgent medical assessment.

Be ready to say when the fever began, the highest reading, the thermometer method, medicines already taken, fluid intake, urine output, travel or sick contacts, and associated symptoms. Ask whether an examination or testing is needed and which changes should trigger reassessment.