Mebhydroline napadisylate is a medication that belongs to the class of antihistamines. It is used to treat allergic rhinitis (hay fever) and allergic skin conditions [Wikipedia]. It is not available in the United States, but it is sold under brand names such as Bexidal and Diazolin in other countries [Wikipedia].
Here's how it works: allergic reactions are caused by the release of a chemical called histamine in the body. Histamine causes symptoms such as sneezing, itching, runny nose, and watery eyes. Mebhydroline napadisylate works by blocking the action of histamine, thereby relieving these allergic symptoms [Wikipedia].
However, it is important to note that mebhydroline napadisylate can cause drowsiness, so it is not recommended to operate machinery or drive a car while taking this medication. Other side effects may include dry mouth, dizziness, and headache [Wikipedia].