What should you know about symptoms before heat stroke?

Heat exhaustion can develop when the body loses fluid and salt while trying to cool itself. A person may have heavy sweating, clammy skin, thirst, headache, tiredness, muscle cramps, dizziness, nausea, or irritability. Confusion, poor coordination, fainting, seizures, or a very hot body suggest a medical emergency rather than a minor heat problem.

A [Fever](/symptoms/fever/) from infection is different from heat illness, but both can make someone feel hot. Vomiting can worsen dehydration; details about [Vomiting](/symptoms/vomiting/) are useful when describing the episode.

Stop activity and move the person to shade or an air-conditioned place. Remove excess clothing, cool the skin with wet cloths or cool water, and use fans if available. If the person is awake, alert, and able to swallow, offer small frequent sips of cool fluid. Do not give drinks to someone who is confused, drowsy, vomiting repeatedly, or unable to swallow safely.

If symptoms do not improve promptly with cooling and rest, arrange urgent medical assessment. A clinician may consider [IV Fluid Therapy](/treatments/acute-and-urgent-care/iv-fluid-therapy/) when oral fluids are not suitable or dehydration is significant.

Call emergency services for confusion, collapse, seizure, severe weakness, breathing difficulty, or inability to drink. Treat suspected heat stroke as an emergency; do not leave the person alone or delay help while trying to cool them at home. Urgent assessment is also needed when repeated vomiting, worsening headache, or faintness continues after moving to a cool place.

Ask which medicines or health conditions increase heat risk, how to plan fluids during outdoor activity, how long to rest before returning to exertion, and which symptoms should trigger emergency action. Mention the heat exposure, activity, fluid intake, and any vomiting or fainting.