Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
University of California
Division of Agriculture and Natural Resources

Heat illness symptoms and first aid

By Howard Rosenberg, UC Cooperative Extension specialist emeritus

Heat rash
Acute skin inflammation and clogging of sweat ducts. Regarded as the least severe of heat illnesses. Though it usually causes only temporary discomfort, it can lead to a bacterial infection that shuts down the function of sweat glands.
Advice: Cleanse the affected area thoroughly and dry completely. Calamine or other soothing lotion may relieve discomfort.

Heat syncope
Loss of consciousness, generally sudden, due to lack of sufficient blood and oxygen to the brain. Greatest danger is secondary injury from a fall. Most likely to affect people not yet acclimatized to work in hot environments. Heat stress can cause it by diverting blood to extremities or lower body at the expense of the brain.
Advice: Rest, ventilate, and drink plenty of water or electrolyte fluids.

Heat cramps
Heavy sweating, thirst, and painful, involuntary muscle contractions -- most commonly in calves, thighs, arms and abdomen. Often extremely uncomfortable and can be completely disabling. Typically occur during or after hard work and are induced by electrolyte deficiencies that result from extended periods of intense sweating.
Advice: Rest and drink plenty of water or electrolyte fluids.

Heat exhaustion
Symptoms include fatigue, headache, dizziness, muscle weakness, nausea and chills, tingling of hands or feet, confusion, loss of coordination, fainting and collapse. Occurs during work and results from dehydration, lack of acclimatization, reduction of blood in circulation, strain on circulatory system and reduced flow of blood to the brain.
Advice: Rest in the shade or a cool place. Drink plenty of water (preferred) or electrolyte fluids.

Heat stroke
The most extreme consequence of heat stress, a medical emergency that can occur suddenly if heat exhaustion is not treated. Skin is hot and dry, body is typically hotter than 104 degrees and no longer able to cool itself, and mind is confused, delirious or convulsive. Brain damage and death may result.

Immediately move to coolest place available, loosen clothing, fan and douse or spray the body continuously with a cool liquid, begin to replenish body fluids by drinking, and summon or rush to aid. Get medical attention or/and transport to a medical facility as soon as possible.

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