By Marcello Cherchi, MD PhD
For patients
Meclizine is a pill that helps some people who are dizzy or who have motion sickness. Meclizine can make you feel sleepy or make it hard to think.
For clinicians
Overview
Meclizine is an orally-administered medication that has anti-histaminic and anti-cholinergic activity. It is used in the management of motion sickness and some otologic causes of disequilibrium. It is generally well-tolerated. Adverse effects are similar to other medications with anti-histaminic activity (fatigue, dry mouth) and anti-cholinergic activity (impaired psychomotor function). It probably has some vestibular suppressant effects, and thus may influence eye movements. It is currently available over-the-counter in the United States.
Introduction
Meclizine hydrochloride came into medical use in the 1950s.
Pharmacology
Meclizine is a piperazine derivative that has anti-histaminic and anti-cholinergic activity. Orally ingested meclizine begins to take effect in about an hour (Wang et al. 2012).
Relevance in otoneurology
Meclizine has been scrutinized in a double-blinded study in the treatment of motion sickness and disequilibrium secondary to inner ear problems, and was found to be superior to placebo (Cohen and DeJong 1972). Some studies report meclizine to be less effective than transdermal scopolamine (Dahl et al. 1984; Schmitt and Shaw 1986). A study in the context of an emergency department reported meclizine’s effect to be comparable to diazepam (Shih et al. 2017) in the acute treatment of “vertigo.”
Cautions and contraindications
Meclizine is generally well-tolerated, though common adverse effects include those typical of medications with anti-histaminic effects, such as fatigue and dry mouth. There are reports from the extremes of the side effects spectrum ranging from none (Kutscher et al. 1966) to transient but significant cognitive impairment (Molloy 1987) — the latter presumably attributable to the drug’s anti-cholinergic activity.
Meclizine can have modest but measurable effects on psychomotor function (Paul et al. 2005). Meclizine can also affect some eye movements (Cohen and DeJong 1972), and although this influence is inconsistent, clinicians should take it into account when interpreting studies of ocular motor function. This can be especially important in the management of benign paroxysmal positional vertigo (BPPV), in which the presence of BPPV (and thus the efficacy of canalith repositioning procedures) is often judged by the presence of positionally-induced nystagmus.
Early studies (Sadusk and Palmisano 1965; Yerushalmy and Milkovich 1965) found no convincing evidence of teratogenicity in meclizine, so the FDA does not currently recommend any restrictions on its use in pregnancy and lactation.
Other notes
Meclizine is currently available over-the-counter in the United States. It is sometimes marketed as Bonine®, and often confused with another over-the-counter motion sickness medication, dimenhydrinate (usually marketed as Dramamine®).
References
Cohen B, DeJong JM (1972) Meclizine and placebo in treating vertigo of vestibular origin. Relative efficacy in a double-blind study. Arch Neurol 27: 129-35. doi: 10.1001/archneur.1972.00490140033006
Dahl E, Offer-Ohlsen D, Lillevold PE, Sandvik L (1984) Transdermal scopolamine, oral meclizine, and placebo in motion sickness. Clin Pharmacol Ther 36: 116-20. doi: 10.1038/clpt.1984.148
Kutscher AH, Zegarelli EV, Hyman GA, Tovell HM (1966) A case report: prolonged use of meclizine hydrochloride with total absence of side effects. Ann Allergy 24: 246-7.
Molloy DW (1987) Memory loss, confusion, and disorientation in an elderly woman taking meclizine. J Am Geriatr Soc 35: 454-6. doi: 10.1111/j.1532-5415.1987.tb04668.x
Paul MA, MacLellan M, Gray G (2005) Motion-sickness medications for aircrew: impact on psychomotor performance. Aviat Space Environ Med 76: 560-5.
Sadusk JF, Jr., Palmisano PA (1965) Teratogenic effect of meclizine, cyclizine, and chlorcyclizine. JAMA 194: 987-9.
Schmitt LG, Shaw JE (1986) Alleviation of induced vertigo. Therapy with transdermal scopolamine and oral meclizine. Arch Otolaryngol Head Neck Surg 112: 88-91. doi: 10.1001/archotol.1986.03780010090017
Shih RD, Walsh B, Eskin B, Allegra J, Fiesseler FW, Salo D, Silverman M (2017) Diazepam and Meclizine Are Equally Effective in the Treatment of Vertigo: An Emergency Department Randomized Double-Blind Placebo-Controlled Trial. J Emerg Med 52: 23-27. doi: 10.1016/j.jemermed.2016.09.016
Wang Z, Lee B, Pearce D, Qian S, Wang Y, Zhang Q, Chow MS (2012) Meclizine metabolism and pharmacokinetics: formulation on its absorption. J Clin Pharmacol 52: 1343-9. doi: 10.1177/0091270011414575
Yerushalmy J, Milkovich L (1965) Evaluation of the teratogenic effect of meclizine in man. Am J Obstet Gynecol 93: 553-62. doi: 10.1016/0002-9378(65)90515-6
