Should i take xanax (alprazolam) before a blood pressure test?

No: Although being anxious about a blood pressure check could raise your blood pressure, e.g. White-coat hypertension, your every day blood pressure is not going to be while you're on xanax (alprazolam) and therefore the reading on xanax (alprazolam) may not be fully reflective of your true bps. A better option would be to check your BP at home regularly and keep a log and take with you to your doctor for review.