A group of kids plays soccer outside in the heat.

You’ve probably seen numerous reports of the hazards of leaving kids even briefly in locked cars during warm weather—notably, potentially deadly heatstroke.

But heatstroke—when the body’s ability to cool itself down fails, leading to a dangerously high body temperature—isn’t just a problem of hot cars. Heatstroke and the heat-related symptoms that lead up to it can happen anytime the body can’t cool itself down properly.

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Infants, for example, can overheat even when they’re not inside a hot car, says Heather Felton, M.D., medical director of University of Louisville Pediatrics and a spokesperson for the American Academy of Pediatrics. A 2017 analysis in Pediatric Emergency Medicine Practice (PDF) notes that heat-related illnesses have occurred in infants exposed to electric blankets, swaddled tightly in too many blankets, and more.

And in older children and adolescents, being active, exercising, or playing sports can also cause the body to become overheated, especially in hot and humid weather. This appears to be common in kids: About 48 percent of emergency room visits for exercise-related heat illnesses between 1997 and 2006 occurred in children and adolescents 19 and younger, according to a 2011 study in the American Journal of Preventive Medicine

And as with heatstroke that occurs in children left in hot cars, the temperature doesn’t need to be swelteringly hot for exercise-related heat illness to occur, says Lara McKenzie, Ph.D., the 2011 study’s author and principal investigator in the Center for Injury Research and Policy at Nationwide Children’s Hospital in Columbus, Ohio. “Exertional heat-related injuries don’t require really extreme ambient temperature,” she says.

Children, she says, may be more prone to heat-related problems. Their smaller bodies can heat up faster than adults’, and children sweat more slowly than adults.

Here, we explain what parents and caregivers need to do to prevent heatstroke in kids, how to spot the signs of a potential heat-related emergency, and what to do if you suspect heatstroke.

Prevent Heatstroke in the First Place

It’s important for adults to remember that children may not realize that they’re getting overheated. For example, young athletes may try to impress peers or coaches by pushing through any discomfort. And while most of the exercise-related heat injuries in youths analyzed in the American Journal of Preventive Medicine study were incurred during sports, activities such as yardwork and other types of recreation can also lead to heat-related illness. A notable activity that may get overlooked in adolescents, according to Alex Diamond, D.O., M.P.H., associate professor of orthopedics and pediatrics and director of the Program for Injury Prevention in Youth Sports at Vanderbilt University Medical Center, is band practice, which may involve carrying a heavy instrument and marching outside on hot pavement.

And even during unstructured play, kids “can get to be so wrapped up in what they’re doing,” Felton says, that they may not realize they need a break.

That’s why it’s important for parents, caregivers, coaches, or other supervisors to impose breaks and to ensure that their charges know it’s okay to take a break and get a drink. Here’s what else to do:

Keep kids hydrated. According to the American Academy of Pediatrics, when children are properly hydrated, they don’t have any more difficulty regulating their body temperatures than adults do when they’re active in the heat. The problem is that “kids aren’t adequately hydrated most of the time when they’re participating in activities and sports,” Diamond says.

Adults need to remind kids to take a break from play and get a drink of water, and encourage them to carry water with them outside. If kids are participating in organized sports or activities at camp or once school starts, counselors and coaches should schedule water breaks every 15 to 20 minutes and make sure kids are drinking plenty of water before and after the activity or practice.

Watch the weather. Heat and humidity both raise the risk of heat-related illness. Humidity reduces the effectiveness of the body’s natural cooling mechanism—the evaporation of sweat off your skin—because when the air is humid, moisture doesn’t evaporate as easily. Heat index is a measure of temperature that takes into account both heat and humidity, so keep an eye on the weather for that metric.

If the heat index is higher than 91° F, the adults in charge should reschedule activities or practices to cooler parts of the day (earlier in the morning or later in the evening), and increase the number of rest and water breaks during the activity, according to UpToDate, an online decision-making tool for doctors from Wolters Kluwer. A heat index of 126° F or higher means that any outdoor activities should be canceled.

Allow time for children to become acclimatized. Often, acclimatization is recommended in organized sports—if kids are just starting team practices, for instance, after being away from them for the summer, make sure they don’t start with a full-blown workout. Parents should make sure that coaches begin slowly and ramp up conditioning over a 10- to 14-day period.

But acclimatization is important outside of sports, too. For example, a family from a colder climate vacationing in a hot or humid locale might need to acclimatize for a few days before safely jumping into a daylong hike.

Keep cool. In heat and humidity, make sure children dress in only one layer of light-colored, lightweight clothing. Stay in air-conditioned spaces if possible. And consider swimming—according to the American Academy of Pediatrics, swimming is an easy way for kids to stay active while also keeping cool.

Know the warning signs of heat-related illness. Less serious heat-related conditions, such as heat cramps or heat exhaustion, can make youngsters very uncomfortable and can precede heatstroke. Catching any of these symptoms early can help prevent someone’s condition from progressing to heatstroke.

If you notice that a child seems tired or weak, or has muscle cramps or spasms, a quickened pulse, headache, nausea, or cold, clammy skin, it’s time for him or her to take a break, find a cool place to rest, and drink water.

Also, know that these warning signs aren’t always present ahead of time, so it’s important to know what heatstroke looks like.

What to Do If You Suspect Heatstroke in Kids

The two key signs of heatstroke are a rectal temperature of 104° F and changed mental status—confusion, dizziness, fainting, and aggression are some possibilities.

It can sometimes be difficult to discern these symptoms—you probably won’t be able to ascertain someone’s temperature immediately, and some of the symptoms of heatstroke and heat exhaustion, such as nausea, vomiting, and dizziness, do overlap.

It’s best to err on the side of caution, however, because heatstroke can be fatal. If you notice any symptoms that make you suspect heatstroke in kids, take action immediately: Start cooling the person down, and have someone call 911.

The best way to cool someone if you suspect heatstroke is with an ice bath—Diamond says sports teams should have an inflatable pool or tub set up filled with ice water for every practice. If you don’t have an ice bath on hand, use whatever’s handy to cool the person down—soaked towels or a garden hose—or take them quickly to an air-conditioned space indoors.

Finally, a note about sweating: In some cases of heatstroke, people stop sweating because they’re so dehydrated that they have nothing left to sweat, Felton says. But that’s not always the case—a person can be dripping sweat and still have heatstroke, especially an athlete, Diamond says, so adults shouldn’t rule out heatstroke just because a youngster is still sweating.