Stress, exercise, and even a few drinks the night before your doctor's appointment can push your blood pressure up. So it's often difficult to tell whether an unusually high reading at the doctor's office means you have high blood pressure—or, if you have already been diagnosed with hypertension, that it's worsening— or whether a work deadline has temporarily inflated your numbers.
To offset this problem, many doctors encourage people to monitor blood pressure on their own. Home monitoring is especially useful for people with white-coat hypertension or labile hypertension, as well as to track responses to exercise, medications, or changes in treatment. It gives a more accurate idea of your blood pressure. It can help fine-tune the strategy for keeping your blood pressure in check. And it just might make you more invested in controlling a problem that has no symptoms until it spawns a heart attack or stroke or leads to heart or kidney failure.
Before you use your home monitor the first time, check your machine against the one in your doctor's office. When you first start to check your blood pressure at home, measure it early in the morning, before you have taken your blood pressure pills, and again in the evening, every day for a week. After that, follow the plan your doctor recommends. And don't panic if one reading is high. Keep in mind that your blood pressure changes constantly throughout the day.
Many blood pressure meters store a week's worth of readings, or more. If yours doesn't, keep a record so you can show your doctor. There are some apps that will do this for you. Some even take the readings directly from the monitor, so that you don't need to write them down.
Doctors warn, however, that home blood pressure monitoring can become too much of a good thing. Just as getting on the scale several times a day is counterproductive when it comes to losing weight, overly frequent monitoring can create anxiety over small fluctuations without contributing to long-term blood pressure management.
Choosing and using a home blood pressure monitor
Most pharmacies have machines that customers can use free of charge, but a home monitor is more practical for taking daily readings. Your doctor may be able to lend you a blood pressure monitoring unit temporarily. If you need to buy the equipment for long-term use, your insurance plan may cover the expense.
There are dozens of home blood pressure monitors on the market, ranging in price from about $50 to $100. For best accuracy and ease of use, buy one with a cuff for the upper arm that automatically inflates and that automatically records the pressure. Models that store readings for a week or two can simplify record keeping. Be sure to choose one with the correct cuff size—the inflatable part should completely cover at least 80% of your bare upper arm. (If the cuff is too small, you can get a reading that is too high.) Test it in the store to be sure it's easy to use. Note that the AHA doesn't recommend wrist or finger home blood pressure monitors, as they are not as reliable.
For more on getting your blood pressure under control, buy Controlling Your Blood Pressure, a Special Health Report from Harvard Medical School.