Harvard Men's Health Watch

How accurate are drugstore blood pressure machines?

Ask the doctor

blood pressure cuff
Image: Bigstock

Q. My doctor recommended I routinely check my blood pressure between office visits. Are pharmacy blood pressure machines accurate?

A. If you are able to obtain an electronic home blood pressure monitor, this is a better option than a store-based machine. There are number of concerns about the accuracy of these machines, which are located in pharmacies or grocery stores.

The first is their one-size-fits-all approach. One of the most important factors in obtaining an accurate blood pressure reading is proper cuff size. There are three common cuff sizes ranging from 22 centimeters (cm) to 44 cm. An improper cuff size can lower or raise the blood pressure reading.

Another issue relates to the maintenance of these machines. Currently, there are no requirements to test their accuracy. Previous studies have suggested the machines become less reliable after a few years.

Also keep in mind that blood pressure should be measured after you have sat quietly for about five minutes, with your arm resting at heart level on a table or armrest. This is often not the case when you rush through a grocery store.

Your best bet is to invest in an electronic home blood pressure machine, which often costs about $40 to $60. Make sure to buy a machine with an arm cuff, which is more accurate than a wrist cuff. Bring your machine to your doctor's office to compare its reading to their measurement.

—William Kormos, MD
Editor in Chief, Harvard Men's Health Watch