Are drug store blood pressure machines accurate?

Yes,: My experience indicates they are accurate. Results may not reflect the same number as at your doctor's office, however, if you use this same machine continually it will be a consistent number. If your BP is going up or down it will show trending to share with your provider.

They can be: Talk with the pharmacist to make sure that it has been calibrated and to make sure it is the proper size for you.

Yes, Probably: Ask your pharmacist whether theirs has been calibrated (tested for accuracy) recently. Make sure you don't have clothing on your arm when you test. It may be that the readings are actually more accurate than those done in a health care setting, where you may have some anxiety about the results, the infamous "white coat syndrome".

Depends: It is your BP trend that matters, so if you take your BP at the same drug store each time it should be on average, close to what your BP is. But remember the correct way to take BP is in sitting position resting for 5 min. (we don't do it right in the doctor's office either).

Most of the time: Most of the larger more permanent blood pressure machine in supermarkets and drugstores are usually decently accurate. Of course, nothing beats a good old stethescope and cuff.