DEAR DR. DONOHUE: Please address the subject of wildly fluctuating blood pressure readings. A couple of years ago, my 87-year-old father was taken off blood pressure medicines because his readings were OK. For the past year, he has had extremely low readings when he stands up. He has been to doctors and the emergency room on several occasions. At times, his pressure is quite high. He has been put on fludrocortisone for the low pressure. I have read about Shy-Drager syndrome and wonder if he might have it. Please give your advice on his low blood pressure. — P.M.

ANSWER: When people stand, their bodies have to make quick adjustments, because blood pools in the legs while they sit. As much as a pint to a quart of blood is taken out of circulation. Blood pressure drops. Reflexes save the day. They get the heart beating faster, and they make arteries constrict. Blood pressure returns to normal promptly. In older people, those reflexes don’t work. Their pressure drops when they rise from sitting or lying, and it stays low. They become dizzy and might even faint.

Before your father changes position, he must tense and relax his leg muscles for a couple of minutes. This muscle action pumps blood out of his legs. It doesn’t pool in them when he rises. After he’s standing up, have him cross one leg over the other. That keeps pressure up, too. He ought to get some custom-fitted elastic stockings. They prevent blood from pooling. If he can handle it, have him drink two glasses of water in three to four minutes before rising. That keeps pressure up for about 20 minutes. His medicine helps him retain salt and water, and that keeps pressure up. If he has trouble on rising out of bed in the morning, place 6-inch blocks under the posts at the head of his bed.

I don’t know if he’s taking medicine for high blood pressure. If his pressure stays high at other times, he needs them.

Shy-Drager syndrome is now called multiple system atrophy. It’s due to a malfunction of the autonomic nervous system, the part of the nervous system over which we have little control. It has a role in maintaining normal blood pressure. This syndrome usually strikes at an age younger than your father’s and is often associated with symptoms that look like those of Parkinson’s disease. Although fluctuating blood pressure is one of its signs, I don’t think your dad has it.

DEAR DR. DONOHUE: You and others have written about the many health advantages from drinking coffee. This is pleasant to learn, although somewhat surprising. About a year ago, I read that research had shown a significant difference in the numbers of colon cancer patients, with coffee drinkers having more cases of cancer than those who consumed decaffeinated coffee. Is this true? — A.R.

ANSWER: You mean it’s surprising to hear medical people say that something enjoyable is good for you?

The latest information I have on coffee says: “There is no evidence that caffeinated coffee increases the risk for any cancer.” This study said nothing about decaf. I take it that it, too, is free of any association with cancer.

DEAR DR. DONOHUE: Skin tags!

What are they? How do you get them? How can you get rid of them? How do you stop from getting them in the first place? — M.C.

ANSWER: Skin tags are outgrowths of the skin. Older people get them. Someone has called them the adornments of aging. At least a quarter of older people have them.

No one knows the cause, other than aging. A doctor can snip them off, freeze them or dry them up with an electric current.

They appear mostly on the neck, under the arms, beneath the breasts and in the groin. They’re not a sign of illness. They aren’t and don’t become cancer.

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.