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Recognizing the Signs of Heat Stroke and Related Illnesses

Do you know the difference between heat stroke and heat exhaustion? Read on to find out.

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Heat-related illnesses infographicConstruction Pro Tips

What is Heat Stress?

Heat stress is an umbrella term that includes all manner of heat-related illnesses including heat rash, heat syncope (fainting), cramps, heat exhaustion and exertional heat stroke. It’s a stealthy safety hazard that can come up on people quickly and without much warning. Our thirst mechanism doesn’t kick in until we’ve lost 1.5 to 2 liters of fluid. And relying on the urge to drink as a sign that you’re dehydrated is even more unreliable an indicator during exercise. Even more frustrating, there’s no set progression of symptoms that build slowly and then crescendo at lethal heat stroke. You don’t have to have heat rash or cramps or even feel poorly to be suddenly rushed into the throes of heat exhaustion or heat stroke. But you’re in luck: here’s a comprehensive guide for warm-weather woes, with smart treatment suggestions for each.

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close up of skin with heat rashjaojormami/Shutterstock

Signs of Heat Rash

Heat rash, also known as prickly heat, occurs when sweat does not evaporate properly and instead clogs the sweat ducts. These tiny red blisters, called papules, can show up on people wearing clothing that are too restrictive and people taking certain medications, such as the bladder stimulant bethanechol (Urecholine) and the hypertension drug clonidine (Catapres).

The mildest form, miliaria crystallina, is not itchy, but the more serious version, miliaria rubra, comes from deeper in the skin and is quite itchy. Both kinds tend to go away as people lower their body temperature.

If you notice one of your workers developing heat rash, have them sip cool water, rest in the shade and apply cold packs to their neck, groin and armpits. Some experts suggest using over-the-counter hydrocortisone cream or calamine lotion for the itch, but the Centers for Disease Control say that’s not a good idea.

Read about portable sunshades and moisture-wicking clothing made with workers in mind.

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What is Heat Syncope?

Heat syncope is otherwise known as orthostatic dizziness or just plain fainting. It happens when the body is trying to cool itself and dilates blood vessels so much that blood rushes from the head. Move the afflicted worker to a shady or air-conditioned area, and elevate their feet to coax blood back to the head. When the worker comes to, offer plenty of water.

Here are 12 jobsite safety tips to help keep you and your crew protected.

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Heat Cramps

These are painful, involuntary muscle spasms most often experienced in the quadriceps, hamstrings and calves, arms and abdominals. Mild nausea is a common side complaint. Stretch and hold the afflicted muscle for a full 20 seconds, then massage gently and apply pressure with wraps or compression socks. Most importantly: Provide water and shade to help lower body temperature.

Check out our favorite functional, hard-working and practical work clothes.

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Heat Exhaustion: What is It?

Heat exhaustion is a medical emergency. Look for flushed skin, profuse sweating, dark-colored urine, dry mouth, headache, nausea, vomiting, dizziness, confusion, lack of coordination and weakness.

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Heat stress, overheated worker

How to Treat Heat Exhaustion

Get the affected person’s body temperature down as fast as possible. Get them into air conditioning or under shade. Have them lie down with feet elevated. Apply towels dipped in ice water. Have them drink two quarts of water over a one-hour period, but make sure they don’t drink more than 2 quarts. If they don’t improve, or they seem to worsen after 30 minutes, call for an ambulance. The line between heat exhaustion and heat stroke can be fuzzy. If the situation looks grim, experts say don’t risk it; call as soon as possible for medical help.

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What is Exertional Heat Stroke?

Heat stroke can be lethal, and it can also permanently damage the brain and other internal organs. Heat stroke’s abrupt onset may be preceded by headache, vertigo or excessive fatigue. Look for little or no sweating, dry or clammy skin, fatigue, nausea, incoherent speech, acute mental confusion, an elevated pulse, and rapid breathing.

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How to Handle Exertional Heat Stroke

Call for an ambulance. While you’re waiting for the medics to arrive, cool the body as much as possible to prevent long-term damage. Strip off clothes and wrap his body in ice water-soaked sheets, leaving only his face exposed. If that’s not possible, move him to the coolest spot available, fan cool air over his body, and wet his skin with several cold cloths.

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Construction Pro Tips

Heat Illness: The final word

Working in heat can be hazardous, but people tend to handle it better the more they do it. Keep in mind that it can take 7 to 14 days for people to acclimate to work in hotter environments. And, even seasoned hot-weather workers need rest, cool water, and Personal Protection Equipment (PPEs), such as a cooling vest and cooling cloths.

Remember: When you’re aware of the signs of all the various heat-related illnesses, you’re better prepared to prevent and treat them.

Alyssa Ford
Alyssa Ford is a long-time freelance journalist in Minneapolis. Her published credits include the Star Tribune, Utne Reader, Crain's,, Minnesota Monthly, Midwest Home, Experience Life, Artful Living, Momentum, Minnesota, and many others. She is a past president of the Minnesota Society of Professional Journalists.