What types of allergy medications are safe to take after gastric byp surgery?

I had bariatric surgery at the end of April this year. I know I'm not allowed to have certain medications (as it will hurt my stomach). Well, I am suffering more than ever before with my seasonal allergies - it's crazy! I have Reactine (from last allergy season), but I'm not sure if I can take it? I have been trying to find some literature on the subject, with no luck! Can anyone help me out??