DEAR DR. DONOHUE: I had little time to spend outdoors this summer, but now I have time to spend in the sun. I want a healthy tan, since I look like a ghost. Can you give me some tips? What is the best way to treat a sunburn? – R.K.

ANSWER: You’ve come to the wrong person to ask about a healthy tan. I don’t believe there is such a thing.

The ultraviolet-B rays of sunlight produce sunburn and damage DNA of skin cells. That sets the stage for skin cancer later in life. Prolonged exposure to the sun is more dangerous before age 20, but it stays dangerous throughout life.

Ultraviolet-A rays penetrate more deeply into the skin than UVB, and they damage the connective tissues beneath the skin. They promotes wrinkles and thick, leathery skin. They also add to UVB’s potential to cause skin cancer.

If you insist on worshiping the sun, use a sunblocker with an SPF – sun-protection factor – of at least 15. Get one that protects against both UVB and UVA. All sunblockers protect against UVB, but not all filter out UVA. If you see on the list of ingredients such things as avobenzone, titanium dioxide or zinc oxide, then you can be sure that the product keeps UVA off the skin. Apply sunblockers 15 to 30 minutes before going into the sun and reapply them often. A person needs to use at least four ounces of it for a day in the sun.

Minor sunburns are best treated with cold compresses or cool baths to which baking soda or colloidal oatmeal is added. Tylenol helps the pain. So does aspirin, but it shouldn’t be used for children.

I would be most happy if I could convince you that your ghostly appearance is truly healthy.

DEAR DR. DONOHUE: I am pregnant for the first time. I have been an exerciser and runner for 10 years, and I wonder if I can continue during my pregnancy. Can I? – J.M.

ANSWER: Exercise during pregnancy is safe for most women. In fact, it’s encouraged. But you have to check with your doctor. There are exceptions to every rule.

Before the exercise boom, women were told not to exercise during pregnancy. It was thought that any increase in body temperature could cause fetal malformations. However, an exercising woman’s body temperature rarely approaches the danger point, which is set at 102.5 F (39.2 C). Exercising in very hot weather is discouraged.

It was also believed that exercise diverted blood flow from the uterus to the exercising muscles and that this was harmful to the fetus. That is not true. Another fear was that exercise produced smaller babies. That too has been disproved.

The intensity of exercise can be “somewhat hard.” The woman should be able to talk while exercising. She should not be panting for breath. And a woman has to increase her calorie intake to support the calories burned through exercise. She will know if she is doing that if she is attaining the weight recommended by her doctor.

After the first three months of pregnancy, women should not lie on their backs while exercising. The enlarging uterus can compress veins returning blood to the heart.

DEAR DR. DONOHUE: What do you think of the many liniments available for sore muscles and sore joints? Do they really work? I use them, and I like them. I am told I am wasting my money. Am I? – R.T.

ANSWER: There must be a market for them, or there wouldn’t be such a large number or such a demand for them.

Liniments can ease pain. I don’t find much evidence that they actually heal. The ingredients in them produce a sensation of heat or cold, and those sensations block pain signals from reaching the brain. These liniments are counter-irritants and contain ingredients such as camphor, menthol or methyl salicylate.

Capsaicin is a special case. It actually depletes nerves of a substance needed for transmission of pain.

If you find them helpful, you’re not wasting any money.

DEAR DR. DONOHUE: My granddaughter, 25 and recently married, is a regular smoker, and so are most of her friends. She just announced that she is pregnant. I told her that she should give up smoking.

She says that her friends, some of whom have children, told her that their doctors said they should taper off or continue to smoke in moderation during pregnancy because it could be harmful to quit cold turkey.

I don’t like to start family fights and endless recriminations, but nicotine is a known poison. Why risking harming the fetus by not withdrawing from smoking immediately? I would like to know the facts. – J.A.

ANSWER: Pregnant women who smoke often deliver babies of low birth weight. Low-birth-weight infants are more vulnerable to many health problems, including infections. These women are also more likely to have premature babies, and premature babies are quite susceptible to infections and other threats to health.

Nicotine diminishes placental blood flow, so the fetus’s nutrition suffers.

I have never been taught that complete cessation of smoking harms the fetus. I cannot find any support for that in the literature.

On this issue, I am definitely on your side.

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.