Are deprivation tanks ok for people with high blood pressure??

Yes. No. Maybe.: It depends on the person, whether he will be nicely relaxed in the tank; or will be "freaked out", claustrophobic, and racing his mind in the tank. It probably also depends on how well-controlled his blood pressure is on his medications; and on how much his blood pressure changes when going from relaxed emotional states to stressful states. So, the answer is "it varies from person to person".