Dear Dr. Gott: I am constantly dizzy. I was taking 160 milligrams of Diovan for a long time, but my doctor changed me to 150 milligrams of Tekturna. Now I'm dizzy on that. My blood pressure is 118/66, so what causes the dizziness?

Reply: There are a number of causes for dizziness, including vertigo, benign paroxysmal positional vertigo, Meniere's disease, inflammation of the inner ear, migraine headaches and as a result of using specific medications. Dizziness can also result from specific medications, low-blood-pressure readings (hypotension), Parkinson's and other neurological disorders, nerve damage to the legs, inner-ear abnormalities and anxiety.

Your first step is to work with your physician to determine the cause of your hypertension. If there is an underlying condition such as an inappropriate diet, excessive salt consumption, obesity or lack of exercise, take steps to bring the matter under control.

Both medications you have been prescribed treat hypertension. Diovan carries such side effects as headache, diarrhoea, back/joint/stomach pain and dizziness. Tekturna does not carry a side effect of dizziness. You didn't indicate what your blood-pressure readings were prior to being placed on medication. While I don't know the specific numbers your physician is hoping to achieve, you might consider asking if you can reduce the dosage of your Tekturna. While it doesn't come in doses smaller than 150 milligrams, perhaps you can take half-doses, if appropriate. To provide related information, I am sending you a copy of my Health Report 'Hypertension'. Other readers who would like a copy should send a self-addressed stamped number ten envelope and a $2 cheque or money order to Newsletter, PO Box 167, Wickliffe, Ohio 44092-0167. Be sure to mention the title or print an order form off my website at www.AskDrGottMD.com.

Dear Dr. Gott: Is it safe to have blood drawn while on a blood thinner?

Reply: Yes, it is. When you cut yourself, the body's defences kick in to halt the bleeding by forming a clot. The process is known as coagulation and is how things should happen. On the other hand, without that cut and with blood moving through your veins and arteries, clots should not occur. Unfortunately, they do, and for a number of reasons. When they occur, a physician will likely prescribe a drug to bring the disorder in line. Some of the causes are inherited, such as sticky platelet syndrome or factor V Leiden; some are acquired, such as occurs with HIV/AIDs, inflammatory bowel syndrome, obesity, trauma and hormone-replacement therapy. These conditions and a host of others must be checked periodically with laboratory testing so a primary-care physician or hematologist can correctly monitor a patient. The testing performed is commonly a PT/INR and may include a PTT. Simply put, a physician will be able to determine through test results how fast your blood is clotting and whether your medication should be modified.

As an example, people may take prescription Coumadin (warfarin) to reduce the formation of blood clots. This anticoagulant works to prevent heart attack and clots from occurring. There are specific ranges a physician wants a patient to remain in, and the only way to achieve that goal is by testing on a regular basis while the patient is on the drug. Once the fine-tuning occurs and a patient is stable on a specific dosage, testing might only be necessary on a monthly basis.

While we commonly refer to Coumadin or warfarin as a blood thinner, the drug is actually an anticoagulant, as there is no medication that actually "thins" the blood.

Dr. Peter H. Gott is a retired physician and the author of several books, including 'Live Longer, Live Better', 'Dr. Gott's No Flour, No Sugar Diet' and 'Dr. Gott's No Flour, No Sugar Cookbook', which are available at most bookstores or online. His website is www.AskDrGottMD.com. Contact him c/o United Media, 200 Madison Avenue, fourth floor, New York, New York 10016.