What are heat cramps? How to treat muscle spasms from exercise in extreme heat

• Heat cramps are painful, involuntary muscle spasms that occur due to exercise in hot and humid conditions.
• While heat cramps are usually harmless, they can be a sign of heat exhaustion, and may lead to heatstroke, a severe heat-related illness that can result in death without immediate medical attention.
• To treat heat cramps and prevent dangerous heat-related illnesses, it's important to drink lots of water, replenish electrolytes, stop your exercise, and cool yourself down by getting into shade or air conditioning.
• This article was medically reviewed by Jason R. McKnight, MD, MS, a family medicine physician and clinical assistant professor at Texas A&M College of Medicine.

The combination of hot temperatures and physical activity can lead to heat cramps in your muscles — particularly in the calves, thighs, and arms.

Along with heat exhaustion and heatstroke, heat cramps are part of a trio of heat-related illnesses.

"Heat cramps are the least serious of the three, but still may be very painful and alarming," says Rathna Nuti, MD, a primary care sports medicine physician in Dallas.

Here's what you need to know to recognize and treat heat cramps before heat illness becomes more dangerous.

What are heat cramps?

A heat cramp feels a lot like a muscle cramp or charley horse, says Nuti.

The number one reason heat cramps occur — as well as heat exhaustion and heatstroke — is exercise in hot and humid conditions.

Hot weather, along with physical activity, sets the stage for heavy sweating. As people sweat, they lose fluids and electrolytes, which is what causes muscle cramps.

Heat cramps can also be an early symptom of heat exhaustion, which is when your body starts to overheat. If you don't cool yourself down right away, you could develop heatstroke, which can result in death without calling 911 and receiving immediate medical attention.

Here's how to tell if concerning symptoms develop alongside your heat cramps.

However, as long as you heed the warning signs of heat cramps, your risk for heatstroke is low.

"Generally, heat cramps are self-limited and do not lead to severe heat-related emergencies such as heat stroke," says Mohamad Moussa, MD, an emergency medicine specialist and associate professor at University of Toledo.

Treatment for heat cramps

If you're experiencing heat cramps, you should use the following strategies to prevent heat exhaustion or heatstroke.

• Stop exercise and get out of the heat. Physical exertion will lead to sweating, so hit pause on your workout or other physical activities. Don't resume activity for several hours, says the CDC. "Rest in shade or an air-conditioned room," says Nuti. This will help cool down your body.
• Replenish fluids and electrolytes. To treat heat cramps, you can consume a sports drink like Gatorade, says Moussa. This will help replace the fluids and electrolytes lost through heavy sweating, and help your muscles recover. Clear juice such as apple juice can also be a good choice, or any food that's high in salt, says Nuti.
• Massage the cramped area. Slowly extend your arm, leg, or other cramped area. You can stretch and gently knead the muscles to relieve the cramp, says Nuti.
• Stay hydrated. Drinking lots of water is an important strategy to prevent further heat-related illness. When it's hot outside, and particularly if you're exercising, drink water every 15 minutes — even if you're not thirsty. Avoid dehydrating beverages in the heat, like alcohol and coffee.
• Dress appropriately for the weather. If it's hot out, leave off layers and opt for breathable fabrics. "Removing excess clothing during physical activity may help reduce the chance of getting heat cramps," says Nuti.

Seek medical help if these treatments are not effective, and cramps do not abate after an hour. Severe cramps may require intravenous fluids, says Moussa.

Related articles from Health Reference:

• Know the symptoms of heatstroke — and how to treat and prevent heat-related illness
• It's important to recognize the symptoms of heat exhaustion before it turns into heatstroke — here's why
• What is sun poisoning and what makes it different from sunburn