Which medicine for seasonal allergies is most effective?

Most effective med: The most effective medication for seasonal allergies is topical nasal steroid sprays such as qnasl, flonase, nasonex, (mometasone) rhinocort, nasacort, etc. Antihistamines are pretty good for mild symptoms of itching, sneezing, runny nose, but less effective for nasal congestion or stuffiness. Best effect if nasal spray started before symptoms start!