Cetirizine is an antihistamine used to relieve allergy symptoms such as watery eyes, runny nose, itching eyes/nose, sneezing, hives, and itching. It works by blocking a certain natural substance (histamine) that your body makes during an allergic reaction.
Desloratadine is used in adults and children to relieve hay fever and allergy symptoms, including sneezing; runny nose; and red, itchy, tearing eyes. It is also used to relieve symptoms of urticaria (hives; red, itchy raised areas of the skin), including itching and rash.
Loratadine is an antihistamine medicine that relieves the symptoms of allergies. It's used to treat: hay fever. conjunctivitis (red itchy eyes).
Promethazine is used to prevent and treat nausea and vomiting related to certain conditions (such as before/after surgery, motion sickness). It is also used to treat allergy symptoms such as rash, itching, and runny nose.