Heat Exhaustion vs. Heat Stroke: Symptoms and What to Do

Heat exhaustion and heat stroke sit on the same scale, but they are not the same thing. With heat exhaustion you feel weak, dizzy, sweaty and sick, and you usually improve within an hour of resting somewhere cool and drinking fluids. Heat stroke is a medical emergency: the body can no longer cool itself, the temperature climbs very high, and the brain is affected, so the person becomes confused, slurs words, collapses or has a seizure. If you see those heat stroke symptoms, call 911.

Call 911 or go to the ER if someone overheated is confused, agitated, slurring words or acting strangely, faints or can't stay awake, has a seizure, has very hot skin with a high body temperature, stops sweating while still hot, has chest pain or trouble breathing, or keeps vomiting and can't drink. While you wait, move them somewhere cool and start cooling them right away.

Heat exhaustion symptoms

Heat exhaustion happens when the body loses a lot of water and salt through sweat and can't keep up. Common signs include:

• Heavy sweating, with cool, pale or clammy skin
• Weakness, tiredness, dizziness or feeling faint
• Headache
• Nausea or vomiting
• Muscle cramps
• A fast, weak pulse
• Thirst and dark urine, or not peeing much

Heat stroke symptoms

Heat stroke is what happens when the body's cooling system fails. Its signs overlap with heat exhaustion, but the difference that matters most is a change in how the person thinks and behaves.

• Confusion, agitation, slurred speech or odd behavior
• Very high body temperature
• Hot, red skin, which can be dry or still sweaty
• A pounding, fast pulse
• Fainting, seizures or not responding

Heat stroke can damage the brain, kidneys and other organs within a short time, which is why the first step is calling 911 and the second is cooling, not driving across town.

What to do for heat exhaustion

Act early, before it gets worse:

• Stop and get cool. Move into shade or air conditioning. Lie down and raise the legs if you feel faint.
• Loosen or remove extra clothing and gear.
• Cool the skin. Use cool, wet cloths, a cool shower, or a fan over damp skin. Ice packs at the neck, armpits and groin help.
• Sip fluids. Water is fine; a sports drink or oral rehydration drink can help replace salt after heavy sweating. Small sips are easier if you feel sick.
• Rest for the rest of the day. Don't go back out into the heat once you feel better.

If symptoms get worse, or you're not clearly improving within an hour, get medical care.

What to do while you wait for help with heat stroke

Call 911 first. Then cool the person as fast as you can: move them somewhere cool, remove extra clothing, and wet the skin with cool water while fanning. If it's practical, immersing the body in cool water works well. Don't give anything to drink to someone who is confused or not fully awake. Fever medicines don't help heat stroke, because the high temperature isn't a fever in the usual sense.

Why heat illness catches people out in Colorado

Denver summers are dry, and in dry air sweat evaporates almost as soon as it forms. You lose water without feeling drenched, so it's easy to fall behind on fluids. Altitude adds to it: people visiting from lower elevations breathe faster and lose more water, and the sun is stronger up high. Hikers, cyclists, roofers and other outdoor workers, athletes at summer practices, and people at all-day festivals are the usual patients.

Some people are more at risk at any temperature:

• Babies and young children, and adults over 65
• People with heart, lung or kidney disease, diabetes or obesity
• People on certain medicines, such as some blood pressure pills, water pills, allergy medicines and medicines for mental health. Ask your pharmacist or clinician if yours affect how you handle heat.
• Anyone who has been drinking alcohol
• Anyone not used to the heat yet, early in the season or just arrived from somewhere cooler

When to come to urgent care for heat exhaustion

Come in if you've had heat exhaustion and are not clearly better after an hour of rest and fluids, if you can't keep fluids down, if muscle cramps won't let up, or if you still feel weak, dizzy or headachy later in the day. A clinician can examine you, check your vital signs and discuss treatment. When someone is dehydrated and can't drink enough, IV fluids in the clinic may be an option. Any sign of heat stroke is for 911 and the ER, not urgent care.

How to prevent heat illness

• Drink regularly through the day, before you feel thirsty, and more when you sweat.
• Plan hard exercise and outdoor work for early morning or evening.
• Wear light, loose, light-colored clothing and a hat, and use sunscreen; sunburn makes it harder to cool down.
• Take breaks in the shade, and ease into the heat over the first week or two of the season.
• Never leave a child, an older adult or a pet in a parked car, even for a few minutes.
• Check on older neighbors and relatives during heat waves.

What a visit costs

We contract with all major commercial and government plans, including Colorado Medicaid and Medicare. We can't guarantee a commercial plan has us in network; if you turn out to be out of network or your benefits are denied, we charge our self-pay rates instead. Self-pay in-clinic visits are $175, $250 with one moderate service, or $330 at most, depending on the care provided. Every tier is on our cost and insurance page.

Where to find us

Four clinics across metro Denver, all ages welcome, se habla español:

• Hampden (Southeast Denver): 8 AM–11 PM daily
• Littleton: 8 AM–11 PM daily
• Thornton: 8 AM–11 PM daily
• Highlands: Mon–Fri 5–11 PM, Sat–Sun 8 AM–11 PM

Walk in, or book online.