Headache after heat exhaustion: what to know

Heat exhaustion involves loss of water and salts through sweating, together with overheating. A headache may remain after you leave the heat because the body has not fully replaced those losses. Thirst, dizziness, fatigue, excessive sweating, dark urine, and heat intolerance can occur alongside it. Dehydration may prolong recovery, particularly if nausea makes drinking difficult.

Symptoms should trend towards improvement with cooling and appropriate fluids. Confusion, collapse, a seizure, or a very high body temperature raises concern for heat stroke, which is an emergency. A headache alone cannot distinguish the severity, so the whole symptom pattern matters.

Move indoors or into shade, remove excess clothing, cool the skin with wet cloths or a fan, and rest. Take small, frequent sips of water or an electrolyte drink if you are awake and not vomiting. Avoid strenuous activity and further heat exposure until fully recovered. Do not rely on alcohol or very sugary drinks for rehydration. If symptoms do not ease, contact a clinician promptly; you may need supervised treatment.

Call emergency services for confusion, fainting, seizure, loss of coordination, unusual behaviour, severe weakness, repeated vomiting, inability to drink, or a worsening headache after heat exposure. Emergency help is also needed if the person is not improving with cooling or becomes difficult to wake. Do not leave someone with severe heat symptoms alone.

Ask whether your fluid and salt replacement is adequate, when you can safely return to work or exercise, and whether ongoing dizziness or dark urine needs testing. Tell the clinician how long you were in the heat, how much you drank, whether you continued sweating, and whether vomiting occurred.