• Antihistamines block the action of histamine, a potent chemical or mediator causing allergic reactions. If you are sneezing, have nasal itching, runny nose, itchy and watery eyes, or itchy throat and palate an antihistamine is needed. It is much more effective if taken prior to exposure. 
• Decongestants reduce congestion or swelling in nasal membranes and relieve nasal stuffiness. 
• A combination medicine containing an antihistamine and decongestant is chosen for times you are having a combination of symptoms. 

We recommend that most allergy patients stay on a non-sedating antihistamine during their allergy seasons or year-round and add a decongestant as needed. Non- or low-sedating antihistamines that are that available only by prescription include Clarinex®, Allegra®, and Zyrtec®.  Claritin® products are available over-the-counter.