DEAR DR. DONOHUE: My 17-year-old granddaughter is coming to visit me this summer. I am eager to see her. I am a bit apprehensive because she has asthma, and I know very little about it or what to do for it. Should I have an oxygen tank on hand? – C.B.

ANSWER: A typical asthma attack begins abruptly with wheezing and an obvious struggle to move air into and out of the lungs. The problem lies in an asthmatic’s airways (bronchi). They are supersensitive to irritants – pollens, polluted air or unidentified substances. Their airways constrict and fill with thick mucus.

The airway constriction and production of mucus are reversible, a quality not found in many other lung diseases.

More than 17 million people in North America suffer from asthma. Most of them handle the condition quite well and are able to carry on a normal life with all its activities.

The emphasis today is on prevention of attacks. That can usually be accomplished by the daily inhalation of medicines into the lungs and their airways. Cortisone drugs relieve airway irritation, reduce mucus production and stop airway constriction. Drugs not related to cortisone can also be inhaled daily to maintain wide-open, mucus-free airways.

Speak to your granddaughter’s mother. She will know, as will your granddaughter, if any allergies provoke an attack. You can then allergy-proof your house in anticipation of the visit.

For acute attacks, different medicines, often inhaled drugs, come into play. Your granddaughter knows what those medicines are, and a young woman of her age has enough presence of mind to know when and how to use them. You do not need to have an oxygen tank on hand.

The newly printed asthma report provides the details of this relatively common affliction. Readers can obtain a copy by writing: Dr. Donohue – No. 602, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 U.S./$ 6.50 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I lost the sight in my left eye from temporal arteritis. There was a delay in making the diagnosis. Will my vision ever come back? – V.R.

ANSWER: Temporal arteritis (not arthritis) is an inflammation of arteries. The “temporal” is in the name because the arteries at the sides of the head (the temples) are usually involved. Artery inflammation, however, is not limited only to the temporal arteries.

Symptoms include pounding headaches, scalp tenderness and inordinate fatigue.

The gravest complication of this illness is loss of vision. It happens because the arteries that supply one or both eyes can be involved.

Prompt treatment with the cortisone drug prednisone stops the inflammation quickly and preserves vision.

Temporal arteritis often has a twin: polymyalgia rheumatica. It’s muscle pain, usually of the shoulder or hip muscles. The pain peaks in the late evening and again in the early morning. Prednisone is the treatment for it, too, so both illnesses, when present, can be treated with one drug.

I am sorry that you lost the vision of one eye. I wish I could tell you it will come back, but that is extremely unlikely.

DEAR DR. DONOHUE: I have a 12-year-old nephew whose mother, my sister, frequently gives him Sominex because she believes it helps him sleep better. I say this in unhealthy. What do you say? – R.B.

ANSWER: Sominex is an antihistamine drug. Many of the early antihistamines have sedation as a side effect. Sominex is safe, but it should not be used on a regular basis, especially for a 12-year-old. If the boy has trouble sleeping, then his mother ought to take him to the family doctor to find out why he cannot sleep.

I don’t know what your sister means by “sleep better.”

DEAR DR. DONOHUE: We have just moved to Florida and love all the fresh citrus fruits. I offered my neighbor a couple of grapefruits. She said she would love to eat them but couldn’t because she is on blood pressure medicine. My husband and I are on blood pressure medicine, and neither the doctor nor the pharmacist mentioned this to us. Would you enlighten us? – J.H.

ANSWER: Grapefruit and grapefruit juice can cause a peculiar phenomenon with some medicines. They increase blood levels of those medicines. Among the blood pressure medicines affected are Procardia, Adalat, Norvasc, Cardizem, Isoptin and Plendil. They have a similar effect on some cholesterol-lowering drugs, such as Lipitor, Mevacor and Zocor. This is not an exhaustive list of drugs with grapefruit incompatibility.

Since neither your doctor nor your pharmacist said anything to you, I would take that as meaning your medicines are unaffected by grapefruit. The grapefruit-medicine interaction is well-known, and I take it for granted that pharmacies automatically attach a warning label to the medicine container.

For 100 percent assurance, ask the pharmacist about your medicines.

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.