Dymista nasal is a combined medicine used to treat nasal symptoms such as congestion, sneezing, and runny nose caused by seasonal allergies. Azelastine is an antihistamine that reduces the effects of the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. Fluticasone is a steroid that prevents the release of substances in the body that cause inflammation.