Overview
Hot weather can lead to dehydration, heat exhaustion, heat cramps, heat rash, and heat stroke. The body normally cools itself by sweating and moving heat away from the skin, but this can fail when temperatures are very high, humidity is high, or fluid loss is not replaced. Risk may rise during heat waves, outdoor work, sports, travel, or power outages.
Key Symptoms
Early warning signs of heat-related illness can include heavy sweating, thirst, tiredness, dizziness, headache, muscle cramps, nausea, and weakness. Skin may feel hot or clammy, and some people may feel faint. More serious warning signs include confusion, trouble speaking, seizure, loss of consciousness, or a very high body temperature.
Causes and Risk Factors
Heat illness happens when the body gains more heat than it can release. High temperature, high humidity, direct sun, strenuous activity, dehydration, and clothing or equipment that traps heat can all add to risk. Alcohol, some medicines, and certain health conditions can also make it harder for the body to cool itself.
Who Is Affected
Anyone can become ill from heat, but some groups are affected more often or more severely. This includes older adults, babies and young children, pregnant people, people with heart, lung, kidney, mental health, or mobility conditions, and people who work or exercise outdoors. People without reliable cooling, housing, clean water, or electricity may also face higher risk.
Prevention
Plan ahead for hot days by checking local weather alerts and limiting intense activity during the hottest hours. Drink fluids regularly, rest in cool or shaded places, wear light-colored loose clothing, and use a hat or umbrella outdoors. Never leave children, older adults, or pets in a parked vehicle, even for a short time.
Diet and Lifestyle
In hot weather, many people do better with regular fluids and lighter meals rather than heavy foods and alcohol. If you exercise, pace yourself, take breaks, and slowly build up activity if you are not used to the heat. Looking in on neighbors, relatives, and others who may need help is also an important part of heat safety.
When to Seek Medical Care
Seek medical care promptly if symptoms of heat illness do not improve after moving to a cool place and resting, or if there is repeated vomiting, worsening weakness, little urine, severe headache, or fainting. Get advice sooner if the person is older, very young, pregnant, or has a chronic health condition. If you think a medicine may be affecting heat tolerance, speak with a healthcare professional.
When It May Be an Emergency
Heat stroke may be an emergency. Call emergency services right away if someone has confusion, collapse, seizure, trouble waking up, or a very high body temperature after heat exposure. While waiting for help, move the person to a cooler place and try to cool them with cool cloths, water, or fanning if you can do so safely.