Used as an antihistamine in the treatment of allergic conditions such as hay fever, urticaria (hives), and other skin allergies. It helps relieve symptoms like itching, swelling, and redness by blocking the effects of histamine, a substance in the body that causes allergic reactions. Mebhydrolin napadisylate is known for its rapid onset of action and is sometimes formulated in combination with other medications to enhance symptom relief. It is typically administered orally and may be found in syrup or tablet forms, especially in certain regions where it is approved for clinical use.