Hello Betty Owen,

It depends on what blood pressure medications you take.

Grapefruit juice causes the liver to not be able to process some medicines as effectively.  Some of the medications in the calcium channel blocker family of drugs (specifically Procardia/nifedipine) and angiotensin receptor blocker family (specifically Cozaar/losartin) can potentially be made more active and unsafely lower you blood pressure.  The effect of the juice on these drugs can be small or large, and varies with the amount of grapefruit juice you drink. 

There are few blood pressure drugs that absolutely contra-indicated for use with grapefruit juice.  Generally speaking, when taking these medications you should not widely vary the amount of grapefruit juice you consume (i.e. half a grapefruit one day and 2-3 grapefruit the next).  You should discuss further with your own doctor if you BP drugs are safe. 

To your health,

Neil MD