As the temperatures increase, your body needs more water. Dehydration is a potentially dangerous condition, and it’s more common during summer.

“Summer activity commonly causes dehydration secondary to heat and humidity—it’s usually not directly related to a specific activity,” explains Dr. Brian Mahaffey, director of Mercy Sports Medicine and a team physician for the St. Louis Cardinals. “In high school and college athletics, heat illness is the third most-common cause of death. It’s easily preventable by following simple rules.”

Mahaffey educates young athletes and weekend warriors about avoiding dehydration by eating and drinking appropriate amounts prior to activity, taking frequent water breaks, and replacing fluids after activity. He also advises athletes to acclimatize to hot conditions by spending some time outdoors before embarking on strenuous activity and matching activity to one’s current fitness level.

“Besides drinking water, you should replace electrolytes,” Mahaffey says. “During heavy activity in heat regularly, increasing your salt intake is key, especially if you notice that your clothes are dry with white residue on them. This is an increased amount of salt loss in your sweat.”

For those who are simply spending more time in warm outdoor conditions, preventing dehydration begins by listening to your body. “Thirst is the earliest symptom of dehydration,” notes Dr. James Wessely, St. Luke’s Hospital emergency department medical co-director. “If dehydration is more severe, symptoms include weakness, dizziness, light-headedness and cramps, usually in the legs. Symptoms can proceed to confusion, fainting and coma. If one is in the heat, by the time they feel thirsty, they are already dehydrated.”

Mahaffey and Wessely advise continual hydration by sipping water throughout the day. “Otherwise, water consumed quickly is just urinated out,” Wessely notes.

The amount of water a person needs each day depends on the amount of heat exposure, activity, size of the person and medications the person may be taking, Wessely adds. “Eight glasses of water a day may be reasonable for an average person with average activity. However, massive exertion in the heat—such as running a marathon—may require a lot more fluid and should include electrolytes and a small amount of sugar. Gatorade and other sports drinks are good choices.”

Severe dehydration is a medical emergency. If you notice someone who appears exhausted, is staggering or slurring his speech, seems confused or faints, seek medical attention immediately.

“If the person can be placed in a cool place and drink fluids and feels better in a relatively short period of time, say 30 minutes, then medical help may not be necessary,” Wessely says. “But if the person has a lot of medical problems or is taking a lot of medications, then they should seek medical help.”

Both Mahaffey and Wessely say dehydration is an avoidable condition that can be prevented with common sense and caution. So pick up a cool glass of water and enjoy sipping throughout the day.

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