Fever the day after heat exhaustion

Heat exhaustion usually causes sweating, weakness, headache, thirst, nausea or dizziness during or soon after heat exposure. Feeling hot after activity can reflect ongoing heat stress, but a true fever may have another cause, such as an infection, or may indicate a more serious heat illness. Check the temperature with a working thermometer and note when symptoms began. See [Heat Exhaustion](/conditions/heat-exhaustion/) and [Excessive Sweating](/symptoms/excessive-sweating/) for related features.

Rest in a cool room, avoid exercise and alcohol, and drink small amounts regularly if you are alert and not vomiting. Wear light clothing and do not use extreme cooling methods that cause shivering. Record the temperature, fluid intake, urine colour and any medicines taken. Contact a clinician for advice rather than assuming the fever is from the heat. Dark urine and intense thirst can accompany [Dehydration](/conditions/dehydration/).

Seek emergency help for confusion, fainting, seizure, severe weakness, breathing difficulty, repeated vomiting, inability to drink or very hot skin with a change in alertness. Get same-day assessment for a continuing fever, severe headache, worsening dizziness, reduced urination or symptoms that do not settle with cooling and fluids.

Tell the clinician how long you were in the heat, whether sweating continued, and your highest measured temperature. Ask whether you need examination or tests for infection, dehydration or heat illness, and which fever medicines are suitable for your health conditions.