Drink up: An age-by-age guide to staying hydrated

It’s a beautiful weekend, and you spend a full day outside in the fresh air. The sun and activity feel great after a week spent cooped up inside. But as evening falls, you start to feel deeply fatigued, even dizzy, and slightly nauseous. It might be a virus. But after a day of yard work or playing sports, it’s more likely to be dehydration.

Dehydration happens when you lose more fluid than you take in and your body can’t function properly. Normally, your thirst reflex nudges you to drink something to compensate for the water lost through sweating, urinating and breathing. Sometimes, diarrhea or vomiting can make it hard to replace your fluids. But the main reason people get dehydrated? You guessed it: too much fun in the sun.

“When it’s hot, your metabolism goes up as your body works hard to cool itself,” says John Moore, DO, an Aetna medical director. You’re losing fluids even if you don’t notice excessive sweating.

Kids and seniors are at greater risk of dehydration than teens and younger adults. Read on to learn how to keep your family and yourself safe and healthy.

Kids

Special risks: Children under 9 lose fluids more quickly than adults. They often don’t recognize why they’re feeling bad or may not articulate it. Mild dehydration can turn severe during outdoor activities in warm weather or a bout of stomach illness.

Warning signs: Keep close tabs on your kids on hot days, and be alert to the following:

• Chapped lips
• Flushing
• Less frequent bathroom breaks
• Cold or dry skin
• Sleepiness or low energy
• Fast breathing or heart rate    

For babies and toddlers, look for unusual fussiness, sunken eyes, sunken soft spot on the head, or a lack of tears. Read more about how to get quick, reliable answers on family health questions.    

Drink this, not that: Children should drink 8 ounces of water for each year of their age — in addition to other beverages — according to the Children’s Hospital of Orange County in Irvine, CA . For instance, 2-year-olds should drink 16 ounces, 3-year-olds need 24 ounces, and so on. After age 8, kids can continue to drink 64 ounces per day.

Other recommended drinks: Pedialyte or Hydralyte, fruit, low-sugar ice pops, milk

Avoid drinking: sport drinks, full-strength juice, soda

Teens and adults

Special risks: Dehydration is rare among healthy adults. Some exceptions are athletes, workers who spend a lot of time outdoors or in hot conditions, and people with diabetes. Another reason to drink up: Chronic mild dehydration is a major contributor to kidney stones.

Warning signs:

• Fatigue
• Headache
• Dizziness
• Flushed skin
• Dry or sticky mouth
• Infrequent urination 

Drink this, not that: “Although the eight 8-ounce glass rule isn't supported by hard evidence, it remains popular because it's easy to remember,” says Joni Jefferson, DO, a primary care physician in New Jersey. “A person’s real water requirements vary depending on factors such as age, climate, activity level, pregnancy and health status.” Dr. Moore agrees. “If you work or play outside, you probably need far more than eight glasses,” he says. “Experts recommend four to six glasses per hour in extremely hot conditions.” Read about hydration reminder apps and other digital tools to help you reach your health goals.

Other recommended drinks: electrolyte-enhanced water, flavored seltzer, decaf iced tea

Avoid drinking: sport drinks, soda and other sweetened beverages, caffeine, alcohol

Seniors

Special risks: Older adults have a smaller fluid reserve and a weakened sense of thirst. They also overheat more easily, so dehydration can have more serious consequences. If you suspect that an elderly person is dehydrated, get them somewhere cool and shady, and give them water to drink. Cold compresses, cool showers and baths can also help.

Warning signs:

• Confusion
• Difficulty walking
• Dizziness or headache
• Flushed skin
• Sunken eyes
• Inability to sweat or produce tears
• Rapid heart rate
• Low blood pressure

Drink this, not that: The National Institute on Aging recommends that seniors make drinking water a part of their routine. The organization suggests committing to drinking a full glass before you leave the house or each time you take a pill. During heat waves, spend as much time as possible in air-conditioning — at home, a senior center or public library. 

Other recommended drinks: electrolyte-enhanced water, flavored seltzer, decaf iced tea, nutrition shakes like Ensure

Avoid drinking: sugary beverages, caffeine, alcohol

Severe dehydration requires medical attention. “If someone is experiencing an alteration in their mental status or feels dizzy, or if they’re not keeping anything down by mouth, you’d want to come to the emergency department,” says George Becker, MD, medical director for the Department of Emergency Medicine at Valley Hospital in Ridgewood, New Jersey. A doctor can administer intravenous saline solution, which rehydrates faster than drinking water.

By all means, enjoy your time outdoors and stay active. Just remember to take a break to cool off and drink up every hour or so, and remind kids and seniors to do the same.