Summer heat can make you sick, and in some cases kill you, unless you take steps to protect yourself, health authorities have warned as Washington temperatures have soared above 90 degrees.

Most likely to be affected by the heat are people in two groups: the inactive, aged and infirm and the overactive, young and healthy.

The risk of heat-related illness tends to be greatest for alcoholics, people living on the upper floors of high-rise buildings and people using tranquilizers, according to one recent study of the victims of a Midwestern heat wave. The risk tends to be lowest for those in homes with air conditioning, trees and shade and for those who are able to take care of themselves and who take a normal amount of exercise but reduce that exercise during hot weather.

To help you get through this summer's heat, here is a question-and-answer quiz developed by Dr. Sidney M. Wolfe, who once conducted heat research at the National Institutes of Health and who now is director of the Public Citizen Health Research Group, a District-based nonprofit consumer advocacy group.

Q: If I drink enough water to satisfy my thirst, is that enough to keep me healthy when it is very hot?

No. Unfortunately, you have to drink about 1 1/2 times more water than your thirst signals you to drink. For example, if two glasses of water satisfy your thirst, drink a third glass. This applies any time the temperature gets about 80 degrees and you can't spend a significant portion of the day in a cool place.

Q: How much liquid should I drink to stay healthy during hot weather?

One gallon of liquids a day, if you are not on a water- or salt-restricted diet.

Q: Are iced tea and iced coffee good to drink when it is hot? How about a cold beer?

None of those is good because they cause you to lose more fluids.

Q: Are there drugs that can increase the chance of my getting sick when it is extremely hot outside?

Yes. Examples are major tranquilizers, such as Thorazine and Melaril; drugs for treating ulcers and other intestinal problems, such as Atropine or Belladonna; and antidepressants, such as Elavil.

Q: Should I stop taking those drugs if it gets hot?

No. You should consult your doctor on what is best for you.

Q: What precautions should I take before I go jogging in the heat?

Drink one pint of water within 15 minutes before going out to run and one quart of water within three hours before going out to run. Avoid tea, coffee and alcoholic beverages for at least 12 hours before running.

In addition, run in the shade when possible, wear light-colored clothing and a hat. Douse yourself with water during the run. Consult a physician before using diuretics, which promote water loss, or anti-colinergics, which inhibit the body's ability to sweat.

Early symptoms of heat exposure--feeling hot, uncomfortable and listless--are mild and usually pose no threat unless they persist for an unreasonable period, according to a special report published by the U.S. Office of Consumer Affairs. But medical attention is important, the report said, if a person experiences dizziness, rapid heartbeat, diarrhea, nausea, cramps, throbbing headache, dry skin (no sweating), chest pain, great weakness, mental changes, breathing problems or vomiting.

"These symptoms can also signal other major problems, such as heart failure," the report said. So anyone experiencing them should "call a doctor immediately."

One of the most serious conditions caused by hot weather is heat stroke, which the surgeon general describes as "a failure of all body cooling mechanisms" and a medical emergency that demands immediate attention and treatment by a doctor. Symptoms include faintness, dizziness, staggering, headache, nausea, loss of consciousness, body temperatures of 104 degrees or higher, strong rapid pulse and flushed skin. In severe cases, blood pressure drops as circulation fails.

In a normal year, there are about 200 heat-related deaths in the nation, but some summers when high temperatures combine with high humidity for a long period, the number of deaths increases dramatically. It zoomed to 1,265 during a 1980 heat wave, according to one estimate.