What is considered the most effective allergy medication to get?

Depends. Over the counter antihistamines like zyrtec, allegra, and Claritin are effective and safe. The antihistamine xyzal (levocetirizine) is very effective but by prescription. Nasal steroid sprays like qnasl, flonase, Nasonex are the most effective treatment for allergic rhinitis and only available by prescription. Prednisone is very effective but has significant side effects. Injections of steroid not recommended.