Thirst

WHEN TO SEE YOUR DOCTOR

* You are experiencing severe thirst, an increased appetite and excessive urination.

* You also have excessively dry skin, lips or mouth.

* You also feel weak or fatigued.

What Your Symptom Is Telling You

Thirst works something like your car's temperature light: It goes on when fluids are low.

Those fluids can get low from excessive sweating, vomiting, diarrhea, fever, hot flashes, sunburn or dieting. Even sitting for hours in the dry cabin of an airplane can cost you a pint or more of water because of evaporation from your skin and breath. Diuretics or steroid medications can also dehydrate the body.

As your fluid levels go down, your body steals water from saliva, making your mouth feel cottony and dry. If you don't replace fluids at this point, you'll start to feel tired, weak and headachy. As dehydration advances, you could experience dizziness and other severe symptoms.

It all seems so simple: Dry mouth means take a drink. The thirst signal isn't always reliable, however. If you're hiking a mountain trail in the noonday sun, you could be significantly dehydrated before the thirst sensation even begins to kick in, according to Beau Freund, Ph.D., research physiologist at the U.S. Army Research Institute of Environmental Medicine in Natick, Massachusetts.

Another type of thirst—continual thirst no matter how much you drink, along with an insatiable appetite and frequent urination—can be a sign of adult-onset (Type II) diabetes.

This is the most common form of the disease and, true to its name, it targets people over age 40. The problem is that the body has too much blood sugar (glucose). The body tries to dilute the sugar buildup in the bloodstream by pulling fluids from the cells.

Symptom Relief

Thirst is a warning signal that should be heeded," says Dr. Freund. Here are some guidelines.

Drink before you get thirsty. You can't always rely on thirst, says Liz Applegate, Ph.D., sports nutritionist and lecturer at the University of California in Davis. That's especially true as you age, since the years tend to dull your sense of thirst. Drinking a half-cup of water every hour will control mild dehydration, she says. You'll need more, however, if you are perspiring or if the air is hot or dry. Many doctors recommend drinking eight eight-ounce glasses of water a day.

Let your urine be your guide. To guard against dehydration, you need to drink enough so that your urine is clear rather than pale or dark yellow, says Dr. Applegate. Clear urine means you have adequately hydrated your body, she says.

Keep water, water everywhere. Use visual reminders to help you remember to drink enough fluids. Keep a filled bottle of water smack in the center of the fridge, for example. Carry a portable supply of fluid for your desk and car, too.

Drink before, during and after exercise. During a workout, you can lose up to four pounds of fluid before you realize you're thirsty. "To be safe, you need to drink about a half-cup 15 minutes before exercise, then every 15 minutes throughout and following exercise," says Hinda Greene, D.O., staff physician of internal medicine with the Cleveland Clinic­Florida in Fort Lauderdale. If you're feeling weak and tired during exercise, stop and drink a few ounces of water.

For long, sweaty workouts, try sports drinks. When you exercise heavily for more than two hours, you sweat away lots of water and minerals, called electrolytes, that help transmit nerve signals to the muscles. "Drinking water alone is not enough to replace these particles," says Dr. Greene. "You're better off with a sports drink." They contain salt to help you retain water, electrolytes such as potassium, and also glucose, a carbohydrate that speeds the absorption and provides energy. (If you have diabetes or high blood pressure or you're taking a prescription diuretic, ask your doctor before using these products).

Drink hard water. Water softening removes calcium and magnesium, replacing them with sodium. This may trigger thirstiness, says Dr. Greene. If you have a water-softening system in your house, you might want to consider removing it, or at least making sure your tap water is hard.

Check your medications. Let your doctor know that you think your diuretic or steroid is making you thirsty, says Dr. Greene. A lower dose could ease symptoms.

See your doctor for a blood test. Diabetes isn't a treat-it-yourself disease. "If your blood contains high amounts of glucose, you'll need to work with your doctor to get it under control," says Richard Guthrie, M.D., professor of pediatrics at the University of Kansas School of Medicine and director of the Diabetes Center at St. Joseph's Hospital in Wichita. The American Diabetes Association recommends a supervised program that includes both diet and exercise.