About dimenhydrinatemuscarinic antagonist,ethanolamine derivative, first generation h1 antagonist , anti histamine, deliriants, antiemetics,antivertigo.mechanism of action of dimenhydrinateantiemetic and antivertigo action: dimenhydrinate is a salt of diphenhydramine and chlorotheophyllinate. dimenhydrinate produces antiemetic action by its central action on chemoreceptor trigger zone (ctz). it decreases the sensitivity of labyrinth apparatus which transmit stimuli to the ctz and stimulates the vomiting center. antiallergics: dimenhydrinate is a potent h1 receptor antihistaminic agent. it has anticholinergic and central sedative action also. migraine: dimenhydrinate is used in migraine due to its sedative as well as antiemetic actions.