Blog Page | October 2015 Hearing Review
The following is Alan Desmond’s August 18, 2015 blog at his Dizziness Depot column at HearingHealthMatters.org.
What is Meclizine?
Meclizine is an antihistamine with anticholinergic properties. According to Drugs.com, the mechanism of action is described as:
Antiemetic; antivertigo agent—Exhibits CNS depressant, anticholinergic, antiemetic, antispasmodic, and local anesthetic effects in addition to antihistaminic activity.
Depresses labyrinth excitability and conduction in vestibular-cerebellar pathways.
Antiemetic and antimotion-sickness actions result, at least in part, from central anticholinergic and CNS depressant properties.
Back in 2013, I did a three-part series1 reviewing the literature regarding the use of meclizine for complaints of “dizziness.” Today’s post updates and condenses those three posts into one, with some additional new information, hoping that this shorter version might serve as a patient handout.
Most patients complaining of dizziness or vertigo have been prescribed meclizine at some point. For a medication that is so widely used, there is very little solid information, creating potential for confusion regarding application and potential side effects. Meclizine is also packaged under the names Antivert, Bonine, and Dramamine II. So many patients come into our balance clinic having received a prescription for meclizine that I am in the habit of asking them about perceived benefit. After listening to their symptoms (some of which include vertigo, nausea, or motion sickness, but just as many do not), I ask them “What is it that the meclizine is treating?” The most common answer is “the dizziness.”
The term “dizziness” is very vague and can mean many different things. Some types of dizziness can be helped by a temporary prescription of meclizine; many types won’t be affected at all, and some could be made worse. In acute inner ear disease (such as Vestibular Neuritis/ Labyrinthitis or a Meniere’s episode), what is making you spin and nauseous is the brain trying to resolve the conflict between a healthy ear and an unhealthy ear sending different signals to the brain. The brain would rather receive no information from the inner ears than to receive conflicting information. Meclizine can help reduce this conflict and reduce vertigo and nausea. Medication taken to suppress vestibular symptoms ideally should be used only during the acute stage following vestibular insult, typically lasting 3 to 5 days. In order for maximal recovery to take place, the brain eventually must be made aware that a conflict exists, so meclizine must be withdrawn.
Meclizine and BPPV. A therapeutic dosage of meclizine creates a lasting sedating effect only to minimally reduce the intensity of symptoms of benign paroxysmal positional vertigo (BPPV), which last only a few seconds. Canalith Repositioning procedures (also known as Epley maneuvers) are extremely effective in relieving the symptoms of positional vertigo. BPPV does not resolve any faster, and likelihood of future episodes is not affected by meclizine. The AAO-HNS Clinical Practice Guideline for BPPV released in 2008 recommends against the use of vestibular suppressants for BPPV.2
The Physicians Desk Reference lists potential adverse reactions for meclizine, noting that “Drowsiness, dry mouth and, on rare occasions, blurred vision have been reported.” But what about functional impact? Could meclizine potentially make your symptoms worse, or have other undesirable side effects?
Manning et al3 explored the central nervous system effects of meclizine and dimenhydrate (Dramamine I). Their results “demonstrate that both dimenhydrate and meclizine, in recommended doses, produce drowsiness and impaired mental performance greater than placebo.” These authors attempt to “interpret the meaning of the observed decrement in test scores” by comparing their results to the effects of ethanol (alcohol): “Ethanol serves as a unique drug to reference degree of impairment because there are epidemiologic data that relate to blood alcohol concentrations with a known risk (.07%) for being involved in a traffic accident.” Comparison of the data demonstrates that the effect of dimenhydrate and meclizine on mental reaction time is equal to that observed while blood alcohol levels were .04 percent to .06 percent. (In most states, .08 is legally drunk.) A more recent study found that long-term use of anticholinergics has been associated with higher-than-average rates of cognitive deficit and dementia.
The use of centrally sedating medication may impede the benefits of vestibular rehabilitation therapy. Vestibular patients taking vestibular suppressants, antidepressants, tranquilizers, and anticonvulsants ultimately achieve the same level of recovery as patients not taking similar medications, but the length of therapy needed tends to be longer.
The bottom line? Meclizine is helpful for vertigo associated with sudden acute vestibular asymmetry due to Meniere’s disease or Vestibular Neuritis/Labyrinthitis, but should be withdrawn once the acute symptoms have diminished. It is not recommended for complaints of lightheadedness, unsteadiness, loss of balance, or dysequilibrium, whether of vestibular origin or not. Vertigo related to BPPV is better treated through canalith repositioning techniques.
Desmond A. Let’s talk about meclizine. Sept 25, 2013. Available at: http://hearinghealthmatters.org/dizzinessdepot/2013/lets-talk-meclizine
AAO-HNSF Clinical Practice Guideline: Benign Paroxysmal Positional Vertigo (BPPV). Available at: http://www.entnet.org/content/clinical-practice-guideline-benign-paroxysmal-positional-vertigo-bppv
Manning C, Scandale L, Manning EJ, Gengo FM. Central nervous system effects of meclizine and dimenhydrinate: evidence of acute tolerance to antihistamines. J Clin Pharmacol. 1992 Nov;32(11):996-1002.
Alan Desmond, AuD, is the author of two textbooks, several book chapters, and two educational booklets for primary care physicians, all related to dizziness and vertigo. He is a co-author of the Clinical Practice Guideline for Benign Paroxysmal Positional Vertigo, and represents the American Academy of Audiology at the American Medical Assn. He is the director of the new Balance Disorders Program at Wake Forest Univ Baptist Medical Center in Winston-Salem, NC.
Chime in on Alan Desmond’s Dizziness Depot column at HearingHealthMatters.org
Original citation for this article: Desmond A. Meclizine – Condensed. Hearing Review. 2015;22(10):10.