Harvard Heart Letter

Ask the doctor: Why does my blood pressure rise in the afternoon?

Q. I am a 50-year-old woman with newly diagnosed high blood pressure. As diets go, mine is definitely on the healthy side. I do not exercise at a health club, but I do a lot of housecleaning and gardening, and I do walk a fair amount, which I feel is equal to what I would accomplish at a health club. I weigh 150 pounds and my height is 5 feet, 6 inches. I take Toprol-XL. My blood pressure seems to be normal in the morning, averaging 121/74, but in the afternoon the upper number is often in the 140s to 150s. Is it normal for blood pressure to rise like this as the day goes on, especially while on a medication?

A. It's great that you are paying close attention to your blood pressure readings. Beta blockers like metoprolol (Lopressor, Toprol-XL) are not great medications for lowering blood pressure when used all by themselves. So, as the day goes on, and you eat and exert yourself physically, my guess is that the metoprolol is just not strong enough to control your blood pressure. One option is to switch to another medication, such as a diuretic or an ACE inhibitor. If your doctor thinks you need the beta blocker for some other cardiac condition, adding a diuretic or ACE inhibitor to the beta blocker makes sense. In fact, combining low doses of medications that fight high blood pressure in different ways is probably a more effective way to do it than with a high dose of a single medication.

I commend you for staying active, but want to add that the more activity you get, the better. Your blood pressure might fall, and cardiovascular health might improve even more, if you regularly did some aerobic exercise, like brisk walking. Your body mass index (a measure of weight for height) is 24.2, putting you just in the healthy weight category. My guess is that if you lost a few pounds and exercised more, it would help your blood pressure, and you might not need any additional medications.

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