Can heat exhaustion cause a fever?

Heat exhaustion develops when the body loses fluid and salt through sweating and cannot cool itself efficiently. The person may feel hot, tired, clammy, thirsty, or light-headed. A measured temperature can be raised, but heat exhaustion is different from an infection-related fever. Dark urine, reduced urination, headache, and muscle cramps can point toward dehydration. Heat intolerance may make symptoms recur during work, exercise, or time in a hot environment.

Move the person into shade or an air-conditioned room, loosen clothing, and cool the skin with a fan, damp cloths, or cool packs wrapped in fabric. If they are awake and able to swallow, give frequent small sips of cool water or an oral rehydration drink. Stop exercise and rest. Avoid alcohol and very sugary drinks. Do not give fluids to someone who is confused, vomiting repeatedly, or unable to swallow; place them safely and get emergency help.

Call emergency services for confusion, fainting, seizure, severe weakness, trouble breathing, inability to drink, or a very hot body with little or no sweating. These can signal heatstroke, which is life-threatening. Seek medical advice if symptoms do not improve promptly after cooling and fluids, or if the person is pregnant, very young, older, or has a chronic illness. Do not leave someone with suspected serious heat illness alone.

Ask how to distinguish heat illness from infection, how much fluid is appropriate for the person’s health, and when work or exercise can restart. Mention dark urine, persistent dizziness, medicines, and any kidney or heart condition.