DEAR DR. DONOHUE: I have been coughing for what seems like forever. I have used every over-the-counter cough medicine I can get my hands on. No luck. I feel OK otherwise, but the coughing is getting me and those around me down. What can I do?

ANSWER: A cough is a protective reflex that clears the airways. A virus-caused cough lasts about three weeks. Coughs that persist for more than eight weeks are chronic coughs, and treatment for such a cough hinges on finding its cause — not always an easy task. I assume you’re not a smoker. The cure for smokers’ cough is to stop smoking.

A chest X-ray is a standard test for coughers. Sometimes bronchoscopy, a look into the airways with a scope, is necessary.

The three main causes of coughing for nonsmokers are asthma, postnasal drip and GERD, gastroesophageal reflux disease (heartburn). Asthma consists of attacks of airway narrowing, excessive mucus production, wheezing and coughing. Examples of asthma treatment are inhaled medicines like Proventil and Pulmicort. Postnasal drip is the annoying trickle of mucus from the sinuses and nose into the throat. It triggers coughing. Astelin nasal spray often can open the airways and quiet the cough. GERD is the spurting of stomach acid into the esophagus and sometimes into the throat, where it provokes coughing spells. Medicines that decrease acid production get rid of GERD coughing. Omeprazole (Prilosec) is one example.

Medicines have to be considered, too. The blood pressure medicines called ACE inhibitors often are implicated as a cause of coughing. Capoten, Zestril and Vasotec are popular ACE inhibitors.

You’re not going to discover the cause of a cough without a doctor’s help. I mentioned the three major causes of cough, but there are many, many more that must be investigated.

TO READERS: The booklet on colon cancer provides useful information on the causes and cures of this common malady. Readers can obtain a copy by writing: Dr. Donohue — No. 505, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: After having blood clots in my lungs, I was put on Coumadin. My doctor advised me to go easy on vegetables that have vitamin K. He gave me a list of those vegetables. I was quite conscientious about avoiding those foods.

Now I take aspirin to prevent another heart attack. Should I dig up that list of vitamin K vegetables while I take aspirin? — W.W.

ANSWER: Vitamin K takes part in producing blood proteins called clotting factors. Coumadin keeps clots from forming (popularly called “blood thinning”) by interfering with the production of those factors. It works against vitamin K. Eating large amounts of vitamin-K-containing vegetables can undo the blood-thinning effects of Coumadin.

Aspirin prevents clots in a completely different way. It stops platelets from sticking to each other and forming a clot. Platelets are the smallest blood cells. This is an action unlike the action of vitamin K. Aspirin doesn’t interfere with clotting factor production. You can eat all the vitamin K vegetables that you want.

DEAR DR. DONOHUE: My grandparents live in the South. I just came back from visiting them. I was in the sun the whole time. I wanted a tan, and I wanted it in advance of those where I live. I got a tan. I also got circles without any tan. My grandmother says it’s sun poisoning. How do I treat it?  L.O.

ANSWER: A more likely diagnosis is a common fungal infection, tinea versicolor. Selenium sulfide lotion, 2.5 percent, works. So does ketoconazole cream, 2 percent, and ketoconazole shampoo. Nothing works overnight. A suntan is more dangerous to health than tinea versicolor.

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.

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