Will Unisom raise my blood pressure?

Yes, it can and can also raise heart rate. Benadryl can also have this effect. Stop taking it and tell your doctor. Anytime someone has a history of high blood pressure they should avoid first generation antihistamines unless the doctor gives them the okay that their blood pressure is under control. Then you can take it when you need, but it shouldn't be used daily because it will increase your risk of adverse effects.