Heat Illness & Dehydration

Essential guidance

Heatstroke is a medical emergency. Confusion, collapse, seizures or altered consciousness during heat exposure require an immediate emergency call and rapid cooling.

Prevent heat emergencies

Check heat alerts and humidity before departure. Reduce exertion during peak heat, arrange shade and accessible drinking water, and set buddy checks for unusual behavior.

Wear loose breathable clothing, take frequent rest breaks, and consider particular risk for older adults, young children and people with chronic illness.

Recognize warning signs

Heat exhaustion can cause heavy sweating, weakness, headache, nausea, dizziness or faintness. Stop activity and move to a cooler place promptly.

Heatstroke may involve altered mental status, confusion, collapse, seizures or very high body temperature. Skin can be hot with or without sweating; do not wait for sweating to stop.

Respond quickly

Call emergency services immediately for suspected heatstroke. Move to shade or a cooler area and start rapid cooling while help is coming, using cool water and airflow or other cooling techniques as advised by the dispatcher.

Do not force drinks into a confused, unconscious or vomiting person. A fully alert person with milder symptoms may sip cool water; seek care if symptoms persist or worsen.

Plan hydration responsibly

Carry more water than the route normally requires, and arrange a means to obtain safe treated water. Prolonged heavy exertion may require food or electrolyte replacement as well as water.

Avoid rigid one-size-fits-all fluid quantities: requirements vary with climate, activity, physiology and medical conditions.

Field checklist

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Related field guides

Further reading

• CDC — Heat and Health
• NWS — Heat Safety

This reference is educational and is not a substitute for emergency responder instructions, training or medical advice.