Meclizine: A Risky and Possibly Ineffective Drug

Meclizine (available in generic versions only) is a drug that is commonly used to treat symptoms of motion sickness. However, its alleged effectiveness is not based on good evidence, and meclizine carries numerous risks, some of which linger for hours after taking the drug. Therefore, we have designated the drug as Do Not Use.

Motion sickness

Motion sickness symptoms can include nausea, vomiting, sweating, dizziness, malaise (a general feeling of unwellness) and other symptoms, which are often triggered when riding on a ship or airplane or in a car.

Although motion sickness can occur in almost anyone with sufficient provocation, certain individuals are more susceptible to the condition. Women are more susceptible than men, and children are more susceptible than adults, with peak incidence occurring at age 12. Pregnant women and migraine sufferers are particularly susceptible to motion sickness.[1]

Symptoms of motion sickness often can be reduced or eliminated by repeated exposure to the same motion (a process known as habituation); taking deep, regular breaths; looking forward at a stable point, such as the horizon at sea; or lying down.[2]

First-generation antihistamines

Meclizine is one of a number of drugs known as first-generation antihistamines (see table below). Although most first-generation antihistamines are approved to treat nasal allergies and colds, their risks outweigh their benefits for these uses.[3] Second- or third-generation antihistamines (for example, fexofenadine [ALLEGRA] and loratadine [ALAVERT, CLARITIN]) are better options when a medication is actually necessary to treat allergy symptoms.[4]

First-Generation Antihistamines

* Some first-generation antihistamines also are available in injectable forms, which are not covered in this article.
** Available over the counter.
*** Do Not Use first-generation antihistamines to treat nasal allergy symptoms or colds.

Meclizine’s effectiveness

Meclizine was approved by the Food and Drug Administration (FDA) in 1957.[5] Meclizine is currently indicated only for preventing and treating the nausea, vomiting and dizziness associated with motion sickness.[6] It is available with a prescription or over the counter.

Randomized, controlled clinical trials evaluating the effectiveness of meclizine for its approved use are sparse, which is not surprising given that the drug was approved before the 1962 Kefauver-Harris Drug Amendments to the federal Food, Drug, and Cosmetic Act, which required drugmakers to demonstrate the efficacy as well as the safety of their products as a condition of approval.[7] The FDA has not posted on its website the data on which the 1957 approval of meclizine was based.[8]

A small randomized trial, published in 1984, found that use of meclizine reduced the occurrence of motion sickness symptoms in German marines subjected to a simulated sea voyage, but there was no placebo group with which to compare the reduction in symptoms, making it difficult to form definitive conclusions.[9] Two subsequent small randomized trials, published in 2004 and 2007, found that meclizine was not more effective than a placebo or other drugs in preventing nausea and other motion sickness symptoms in chair-spinning tests and in helicopter passengers, respectively.[10],[11] In two of the three aforementioned trials, the medicine scopolamine (TRANSDERM- SCOP) administered as a patch outperformed meclizine in preventing motion sickness symptoms.[12]

Therefore, based on the currently available evidence, meclizine appears to offer little, if any, benefit in preventing or treating motion sickness.

Risks of meclizine

Meclizine, like all first-generation antihistamines, has numerous risks. First-generation antihistamines more easily cross from the bloodstream into the brain than newer antihistamines, leading to increased drowsiness and confusion.[13] A 2005 randomized controlled trial found that a single 50-mg dose of meclizine resulted in cognitive impairment in performing a number of tasks seven hours or longer after ingestion.[14]

Other side effects of first-generation antihistamines are related to their blocking of certain receptors in the body that result in what are known as anticholinergic symptoms. These include dizziness, dry mouth, blurry vision and urinary retention (the inability to empty the bladder completely).[15],[16] The label for meclizine warns of the potential for such symptoms and that the drug should be used with caution in patients with asthma, glaucoma or prostate gland enlargement.[17]

The meclizine label contains the following additional warnings:[18]

• Serious allergic reactions, headache, fatigue and vomiting;
• Use of meclizine in children under 12 years of age is not recommended due to a lack of studies in such patients;
• Pregnant women and nursing mothers should avoid meclizine, unless absolutely necessary, due to the possibility of fetal harm or the drug being excreted into the breast milk, respectively;
• Meclizine should be administered with caution to patients with liver or kidney impairment to avoid the possibility of high concentrations of the drug in the blood;
and
• There is a possibility of harmful interactions between meclizine and certain drugs, including amiodarone (NEXTERONE, PACERONE), bupropion (APLENZIN, FORFIVO XL, WELLBUTRIN SR, ZYBAN), cimetidine (TAGAMET HB), cinacalcet (SENSIPAR), duloxetine (CYMBALTA), fluoxetine (PROZAC, SARAFEM, SELFEMRA), paroxetine (BRISDELLE, PAXIL, PEXEVA), quinidine (NUEDEXTA), sertraline (ZOLOFT) and terbinafine (LAMISIL).[19]

What You Can Do

Do not use meclizine for any condition. Do not take any other first-generation antihistamine for allergies or colds. You should take medication for prevention of motion sickness only if you have moderate-to-severe symptoms when traveling and nondrug approaches have failed. If you require medication, scopolamine is effective and safe for the prevention of nausea associated with motion sickness.[20] However, it has not been shown to be effective for the prevention of vomiting associated with motion sickness, nor for the treatment of symptoms once they have begun. In addition, patients with an eye condition known as angle closure glaucoma and children should not take scopolamine.[21] Elderly patients should use it with caution.

If you take scopolamine, avoid any tasks, such as driving, that require mental and physical alertness for at least three days after taking the drug because it could cause drowsiness. Scopolamine also can cause dry mouth, blurred vision and vision-endangering angle closure glaucoma, dizziness, psychiatric side effects such as agitation and hallucinations, difficulty urinating, intestinal problems, and aggravation of seizure disorders.

References

[1] Priesol AJ. Motion sickness. UpToDate. January 4, 2018. https://www.uptodate.com/contents/motion-sickness. Accessed January 9, 2018.

[2] Golding JF, Gresty MA. Pathophysiology and treatment of motion sickness. Curr Opin Neurol. 2015;28(1):83-88.

[3] Another look at first-generation antihistamines. Worst Pills, Best Pills News. May 2016. /newsletters/view/1034. Accessed January 4, 2018.

[4] Treatment for nasal allergies: An updated review. Worst Pills, Best Pills News. April 2016. /newsletters/view/1027. Accessed January 4, 2018.

[5] Drugs@FDA: FDA-approved drug products. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=010721. Accessed January 4, 2018.

[6] Mylan Pharmaceuticals Inc. Label: meclizine. December 2016. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=595ba2cb-b31f-4cff-b86e-40e72109a582. Accessed January 4, 2018.

[7] Food and Drug Administration. Promoting safe and effective drugs for 100 years. FDA Consumer magazine. The Centennial Edition/January-February 2006. https://www.fda.gov/AboutFDA/WhatWeDo/History/ProductRegulation/PromotingSafeandEffectiveDrugsfor100Years/. Accessed January 4, 2018.

[8] Food and Drug Administration. Drugs@FDA: FDA Approved Drug Products. Meclizine (ANTIVERT). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=010721. Accessed January 4, 2018.

[9] Becker G, Goossens H, Seemann K, et al. [Prevention of motion sickness with a transdermal therapeutic system containing scopolamine. A randomized, comparative double-blind study in the German Federal Navy]. [Article in German] Dtsch Med Wochenschr. 1984;109(49):1881-1885.

[10] Dornhoffer J, Chelonis JJ, Blake D. Stimulation of the semicircular canals via the rotary chair as a means to test pharmacologic countermeasures for space motion sickness. Otol Neurotol. 2004;25(5):740-745.

[11] Estrada A, LeDuc PA, Curry IP, et al. Airsickness prevention in helicopter passengers. Aviat Space Environ Med. 2007;78(4):408-413.

[12] Spinks A, Wasiak J. Scopolamine (hyoscine) for preventing and treating motion sickness.Cochrane Database Syst Rev. 2011; July (6):CD002851.

[13] Carson S, Lee N, Thakurta S. Drug Class Review: Newer Antihistamines: Final Report Update 2 [Internet]. Portland (OR): Oregon Health & Science University; May 2010. Introduction. http://www.ncbi.nlm.nih.gov/books/NBK50554/. Accessed January 4, 2018.

[14] Paul MA, MacLellan M, Gray G. Motion-sickness medications for aircrew: impact on psychomotor performance. Aviat Space Environ Med. 2005;76(6):560-565.

[15] Collamati A, Martone AM, Poscia A, et al. Anticholinergic drugs and negative outcomes in the older population: from biological plausibility to clinical evidence. Aging Clin Exp Res. 2016;28(1):25-35.

[16] De Sutter AI, Saraswat A, van Driel ML. Antihistamines for the common cold. Cochrane Database of Systematic Reviews. 2015;November(11): CD009345.

[17] Mylan Pharmaceuticals Inc. Label: meclizine. December 2016. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=595ba2cb-b31f-4cff-b86e-40e72109a582. Accessed January 4, 2018.

[18] Mylan Pharmaceuticals Inc. Label: meclizine. December 2016. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=595ba2cb-b31f-4cff-b86e-40e72109a582. Accessed January 4, 2018.

[19] Mayo Medical Laboratories. Cytochrome P450 2D6 Known drug interaction chart. https://www.mayomedicallaboratories.com/it-mmfiles/Cytochrome_P450_2D6_Known_Drug_Interaction_Chart.pdf. Accessed January 4, 2018.

[20] Spinks A, Wasiak J. Scopolamine (hyoscine) for preventing and treating motion sickness. Cochrane Database Syst Rev. 2011; July (6):CD002851.

[21] Sandoz. Drug label: scopolamine (TRANSDERM SCOP). October 2017. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4b8cb288-251d-4f99-94d7-a5d0d132729f. Accessed January 9, 2018.