Certain drugs are known to increase blood pressure, including over-the-counter medicines. Flue and cold remedies, birth control pills, antidepressants are only several examples from this long list. In any case, without recommendations of your physician it is not advisable to drop any medicine even if it seems to you that it influences your condition and blood pressure level.
And the last but not the least. Clothes with short sleeves will make your blood pressure check more enjoyable. The matter is that it will be easier to wrap the blood pressure cuff around your arm.
