Medical therapy emphasizes relieving the obstruction with decongestants and topical nasal steroids ... of stasis/colonization diminishes. Antihistamines should be reserved for the atopic CF ...

[52] Topical dual-acting drugs, which combine mast cell-stabilizing properties and histamine receptor antagonism, such as olopatadine and ketotifen, may have greater efficacy in relieving signs ...

Another difference might be how long it takes for you to feel better. Those OTC antihistamines typically start working in about an hour, but it may be a couple of days before the prescription ...