If you mean you have High Blood Pressure (HBP), it isn't antihistamines you should avoid. It's decongestants. There is a difference. Lots of antihistamines are out there without decongestants - Zyrtec, Claritin, Benedryl, Allegra, etc. As long as it doesn't have -D after the name, you should be OK. Avoid the Sudafed series too.