[Jaymz404]

They can. They mostly do it on the left because most people are right handed and blood pressure can be higher in the dominant arm, not by much probably 10 mm Hg maximum really.

At the end of the day, it does not matter but the way I was taught was always to do it on the left arm first.

If your blood pressure is high (hypertension) you check both arms, so you would check the right and that would confirm if a patient had Hypertension.