Diarrhoea after heat exhaustion

Heat exhaustion causes loss of water and salts through sweating, and diarrhoea adds another route of fluid loss. The combination can cause thirst, headache, dizziness, dark urine, weakness, or reduced urination. Diarrhoea may also come from an infection or food exposure that happened at the same time, so do not assume heat was the only cause.

Heat intolerance, confusion, collapse, or a change in alertness is more concerning than ordinary tiredness after heat. A person who cannot drink safely needs prompt medical assessment.

Move to a cool place, loosen extra clothing, and rest. Sip water or an oral rehydration drink slowly; avoid alcohol and strenuous activity. Once settled, choose light food as tolerated and keep monitoring urine, alertness, thirst, and dizziness.

Do not return to heat or exercise while symptoms continue. If you have a medical condition, take regular medicines, or have ongoing heavy losses, ask a clinician which rehydration plan is suitable. A clinician can assess for dehydration when home fluids are not enough.

Call emergency services for confusion, fainting, seizure, severe weakness, very hot skin, difficulty breathing, or inability to drink. Seek same-day medical care for persistent dizziness, dark urine or very little urine, worsening headache, repeated vomiting, blood in stool, or diarrhoea that continues after cooling and rehydration.

Ask whether you need an examination or fluid treatment, how to return safely to activity, and whether infection or another cause should be checked. Describe the heat exposure, sweating, drinks taken, and any change in urine or alertness.