Are you allowed to take nyquil when you are on blood pressure pills?

No

Is NyQuil okay to take if you have high blood pressure

No, Nyquil and High Blood Pressure does not go together. But, if you ask your Pharmacist they can direct you to some options. I have high blood pressure and I am so glad you asked, as Nyquil can give you palpations and make your blood pressure rise. Reading packages when it comes to over the counter medications are a habit for me. As I have had various side effects to many medications. Sounds like you have been there before too.