Dizziness after heat exhaustion: what to know

Heavy sweating lowers body fluid, and heat widens blood vessels. Together, these changes can reduce blood flow to the brain for a while, especially when you stand. Dehydration may also come with thirst, headache, dark urine or continued excessive sweating. Dizziness can feel like lightheadedness, weakness or the room moving; describe which sensation you have.

If symptoms return in a cool place, happen without exertion, or keep recurring, another problem may be contributing. A clinician can assess hydration, blood pressure and other possible causes.

Stop activity and move to shade or an air-conditioned room. Lie down with your legs raised if you feel faint, loosen tight clothing and use cool damp cloths. Sip water or an oral rehydration drink slowly; avoid alcohol. Do not drive, exercise or return to heat until you feel steady and your urine is becoming lighter.

Seek emergency help for confusion, collapse, seizure, trouble breathing, chest pain, severe headache, repeated vomiting or hot skin with worsening symptoms. Get prompt medical advice if dizziness does not improve after cooling and fluids, or if you cannot keep drinks down. These signs need assessment because heat illness can progress.

Ask: Could dehydration still be affecting me? Should my blood pressure or electrolytes be checked? When is it safe for me to return to exercise or work in heat? Tell the clinician when the heat exposure occurred, how much you drank, whether you vomited, and whether you fainted.