When temperatures begin to climb, many of us can find ourselves growing physically uncomfortable. Indoors or out, warm weather can make us lethargic, sweaty, and nostalgic for winter. There are differences, though, between heat exhaustion—a precursor to more serious symptoms—and heatstroke. So what are they? And how can you treat them?

Heat exhaustion happens when the body begins to overheat as a result of exposure to excessive temperatures or high humidity. (Humidity affects the body's ability to cool off, because sweat cannot evaporate as easily in humid weather.) Sufferers may sweat profusely, feel lightheaded or dizzy, and have a weak or rapid pulse. Skin may become cool and moist. Nausea and headache are also common. With heat exhaustion, it’s necessary to move to a cooler place and drink plenty of fluids, though medical attention is not often required.

If those steps aren't taken, though, heatstroke can set in. This is much more serious and involves the body reaching a dangerous core temperature of 104°F or higher. People experiencing heatstroke may appear disoriented or confused, with flushed skin and rapid breathing. They may also lose consciousness. While heat exhaustion can be treated and monitored at home until symptoms resolve, heatstroke is a medical emergency that requires prompt attention by a health professional. Until help arrives, heatstroke should be treated with cool cloths or a bath, but sufferers should not be given anything to drink.

Although young children and those over the age of 65 are most susceptible to heat-related health issues, anyone can find themselves having a reaction to warm temperatures. If you’re outside, it’s best to drink plenty of fluids, wear light-fitting clothing, and avoid being out in the afternoons when it’s warmest. Because sunburn can compromise the body’s ability to cool itself, wearing sunscreen is also a good idea.

While it’s not always possible to avoid hot or humid weather, monitoring your body for symptoms and returning to a cool space out of the sun when necessary is the best way to stay healthy. If you have older relatives who live alone, it’s also a good idea to check on them when temperatures rise to make sure they’re doing well.

[h/t WWMT]