In a double-blind crossover study, meclizine hydrochloride was shown to be significantly more effective than placebo in treating patients with positional and continuous vertigo of vestibular origin. Meclizine reduced the severity and frequency of attacks, as well as signs and symptoms associated with the vertigo. These included nausea, positional and positioning nystagmus, and postural instability. There was no difference in the response of patients with disease of the peripheral or central vestibular system.