Heat Exhaustion and Heat Stroke: Warning Signs, First Aid and When to Call 911

What it involves

MedlinePlus says heat illnesses are caused by exposure to extreme heat or sun and can be prevented by being careful in hot, humid weather. It describes a progression: muscle cramps come first, and if heat exposure continues, they can lead to heat exhaustion and then heat stroke. Heat stroke is when the body can no longer regulate its temperature and it keeps rising.

Who this is for

• Patients who work or exercise outdoors in the heat, including through the humid Florida summer
• Older adults and patients on medicines that affect how the body handles heat
• Patients recovering from a heat illness who want to know when it is safe to return to activity
• Anyone who wants to learn the warning signs before the next hot day

What to expect

• Questions about what happened, how long you were in the heat, and how you feel now
• A review of your medicines, heart history, and how much you drink on active days
• A check of your vital signs and hydration during the visit
• A plan for recovery, a safe return to exertion, and prevention

The three stages

MedlinePlus lays out the signs by stage:

• Early: muscle cramps and pains, often in the legs or abdomen, plus fatigue, thirst, and very heavy sweating
• Heat exhaustion: cool, moist skin, severe thirst, dark urine, dizziness, headache, nausea or vomiting, weakness, and a rapid, weak pulse
• Heat stroke: heat exhaustion symptoms plus a temperature above 104 F (40 C), confusion, slurred speech, seizures, or loss of consciousness

Call 911 right away if

MedlinePlus says to call 911 or the local emergency number if the person loses consciousness at any time, has confusion or seizures, has a fever over 102 F, or has a rapid pulse or breathing consistent with heat stroke. Call as well if the condition does not improve or gets worse despite treatment. Sweating may stop in heat stroke, so a hot, dry person who seems confused is an emergency.

First aid while you wait or recover

MedlinePlus advises having the person lie down in a cool place with feet raised about 12 inches. Apply cool, wet cloths or cool water to the skin, use a fan, and place cold compresses on the neck, groin, and armpits. If the person is alert, give small sips of a sports drink or salted water, about a half cup every 15 minutes. For cramps, gentle but firm massage of the muscle can help it relax.

What not to do

MedlinePlus lists several mistakes. Do not give fever medicines such as aspirin or acetaminophen, since they will not help and may be harmful. Do not give salt tablets, alcohol or caffeine, and do not rub alcohol on the skin. Do not give anything by mouth if the person is vomiting or unconscious. Dehydration from stomach illness has its own steps in the stomach flu and dehydration guide.

Who gets hit harder

MedlinePlus says you feel the heat sooner if you are not used to high temperatures or humidity, are a child or older adult, are already ill, are obese, or are exercising. It also names drinking alcohol in the heat, not drinking enough fluids, heart disease, wearing too much clothing, and certain medicines such as beta-blockers, water pills, and some medicines for depression, psychosis, or ADHD. A medication review is a routine part of a primary care visit.

Preventing it, and returning to exercise

MedlinePlus suggests checking the day's temperature before going out, bringing plenty of fluids, finding shade, wearing loose, light-colored clothing, resting often, and avoiding heavy outdoor exercise in hot or humid weather. After recovering from exertional heat illness, it says to check with your provider before returning to heavy exertion, and to rebuild slowly over several weeks. Muscle cramps without heat exposure are covered in the muscle cramps guide.

Sources

• MedlinePlus — Heat emergencies
• MedlinePlus — Heat Illness