It's not likely that the nonsedating antihistamines would raise your BP -- don't know about the "old line" antihistamines. However, I do notice that the Zyrtec mongraph lists hypertension as emerging in up to 2% of patients in trials for the drug, although there was no proof that the Zyrtec was the cause. But you never know -- I've certainly had a few very atypical side effects from some meds.

Why not just take the antihistamine and keep close tabs on your bp? Discontinue if there seems to be an adverse effect, and maybe re-challenge (try it again after awhile) to prove that it was really the antihistamine that was behind the temporary BP increase.

But again, you're unlikely to have a problem in the first place. I have mildly elevated BP (I take Benicar for it), and haven't noticed any BP-raising effect from Allegra, Claritin or Astelin.

Rick

I hear ya about the bouncing BP. Now, I assume since you're so tuned in to your BP (generally a good thing), you are trying to watch your weight and sodium intake (if your BP is salt sensitive), possibly taking BP med(s), and hopefully exercising (my personal shortfall, although 40mg of no-side-effect Benicar + attention to weight are keeping it at an average of 113/72). If by some chance you're not doing any of the above, I'm sure that's all more significant than whether or not you're taking an antihistamine.

The kind of monitoring you suggest sounds fine. But if "bounce" is a major issue and you REALLY want to try nailing down potential effects, how about this: Go for two weeks without the antihistimine. During this tme, measure your BP at, say, 7AM and 7 PM every day. With each reading, make a note of whether it's a bad allergy day or not. Then do the same thing taking the antihistamine daily for two weeks (even if you normally only take it as-needed). Then take the "Good Allergy Days" and calculate and comapre the average readings between the pre-antihistamine and post-antihistamine periods and see if there's a meaningful increase. Then do the same thing for the "Bad Allergy Day""pre" and "post" averages. Doing it this way helps get around the two counfounding isssues of BP bounce and the tendency for your BP to naurally increase on bad allergy days.

Of course, this all assumes that you don't mind suffering through the untreated allergy symptoms during the no-antihistamine test period!

Again, this is proably all overkill unless you just can't get a sense of whether the antihistamines could be having an effect.

Rick