DEAR DR. DONOHUE: Our family is planning a vacation in July. Our problem is my son, 40, who is allergic to chlorine. He became allergic about 15 years ago. Upon entering the pool, his skin turns red and becomes itchy. Is there anything he can take to avoid this problem? – N.J.

DEAR DR. DONOHUE: Here’s one for you. I decided at age 63 to start exercising. Since I was a competitive swimmer 40-some years ago, I returned to swimming. Here’s where I need your help. I itch terribly after I swim. I think it’s the chlorine in the pool. What can I do to stop the itching? – R.S.

ANSWER: Chlorine in pool water irritates some people, makes a few itch and makes fewer break out in hives. How long do both of your reactions last? Long enough to see a doctor? It would be informative to have a doctor examine your skin and tell you what the reaction is.

Do the outbreaks happen only in chlorinated water? Can you swim in lakes and the ocean without developing an itch? If you can, then I can buy chlorine as the guilty party. If you do break out, then the problem could be the water. Some people get a hivelike reaction from jumping into any kind of water, chlorine or no. That’s aquagenic pruritus. Sunlight, exercise and heat cause similar outbreaks.

Try these tricks. Cover your bodies with petrolatum (Vaseline) before diving into the water, just like swimmers of the English Channel cover themselves with grease. Take an antihistamine before you swim, and get one that isn’t sedating.

I don’t want either of you to get into trouble. Always swim with someone else, someone who can get you out of the water should you have a serious reaction.

DEAR DR. DONOHUE: I am pregnant for the first time. Up to now I have been very active. I run competitively. What kind of exercise can I safely do during pregnancy? If I don’t exercise, I gain weight. – J.T.

ANSWER: Pregnancy and exercise is an FAQ – frequently asked question. The short answer is that pregnant women can and are encouraged to exercise. One reason is to keep the woman’s weight at the prescribed amount.

For women who have been regular exercisers right up to pregnancy, they can continue their programs, but at a reduced level. They can exercise at a “moderate” intensity for 30 minutes, all days of the week if they wish. “Moderate” means the exercise doesn’t leave you so breathless that you can’t carry on a conversation. A woman not being able to talk is a crime against nature.

Pregnancy is not the ideal time, however, to begin exercising for the first time, but all, including previous dedicated couch potatoes, can walk.

Women should consult their doctors about the appropriateness of exercise. They shouldn’t exercise when lying on their backs, particularly in the later stages of pregnancy. The enlarging uterus presses on blood vessels and obstructs the flow of blood from the legs back to the heart. They shouldn’t participate in contact sports. They should not scuba dive.

DEAR DR. DONOHUE: Is it true that exercising less strenuously actually burns more fat than when exercising all-out? I heard that is true, and I would love it to be true. – J.D.

ANSWER: Is this rumor making the rounds again?

It is true that low-intensity exercise derives more calories from burning fat than does high-intensity exercise. With low-intensity exercise, about 50 percent of the calories burned come from fat. With high-intensity exercise, fat burning supplies 40 percent of the calories. Are you happy? Read on.

Examine this more carefully. Say you burn 200 calories from low-intensity exercise. One hundred of those calories represent fat burning. In the same amount of time, high-intensity exercise burns 400 calories. Forty percent of 400 calories gives you 160 fat-burning calories. High-intensity exercise wins.

I made up the example, but I didn’t make up the percentages.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com