What’s the Big Deal About Meclizine?

When I was growing up, I used to go fishing with my Dad.  As we sat, in the dark and wet, freezing in Tillamook Bay in November, he would offer sage words of advice:  “Vertigo?  Meclizine, of course.”*

And, so, through residency and even as teaching faculty, the standard antihistamine treatment for vertigo has always been meclizine – until this past month, when all the meclizine was pulled from our Pyxis due to manufacturing contamination.  So, what would we use as an alternative?

I will not take credit for having performed the most exhaustive of possible literature searches, but, by far, the most fantastic piece of literature I found was from 1968.  This comes from the era of the Cold War and the Space Race, and the folks most interested in effect anti-motion sickness was NASA.  So, among other things, early aerospace medicine was interested in preventing astronauts from vomiting their brains out as they were spun and shaken under otherworldly conditions.  To do so:

“… subjects, male and female, were rotated using the step method to progressively increase the speed of rotation (+2 rpm) after every 40 head movements to a maximum of 35 rpm. The end point for motion sickness was the Graybiel Malaise III total of symptoms short of frank nausea.”


Regardless, what I found interesting – and potentially practice-changing, was that meclizine stunk.  It was, in fact, the worst performing antihistamine of their trial:

What worked best?  Scopolamine plus amphetamine was far superior to any other monotherapy or combination therapy.  However, this isn’t a realistic treatment option.  From these data, at least, probably the best option may actually be promethazine (Phenergan).  And, for what it’s worth, promethazine also comes in suppository form – meaning it can be used as a rescue when the vomiting has already taken hold.

Probably any other sedating antihistamine has some value in meclizine’s absence, but I’m going with promethazine.  In fact, I’m not entirely certain I’ll ever go back ….

“Evaluation of sixteen anti-motion sickness drugs under controlled laboratory conditions.”

* This never happened.

3 thoughts on “What’s the Big Deal About Meclizine?”

  1. In your lit review, did you happen to come across any evidence +/- for valium? I usually use valium as my second line, but a lot of people use it as a first line. I would have never thought of promethazine, but I will try it!

  2. I love metoclopramide (Reglan). Works great. Sometimes I throw in a little diphenhydramine with it. Valium is my fail safe.

  3. Sorry about the holiday delay –

    I didn't perform a real, structure systematic review, so I can't specifically say where benzodiazepines or other dopaminergic agents (metoclopramide) fall in the scheme. Benzodiazepines are frequently mentioned in various reviews as an effective agent for termination of dysequilibrium syndromes, however.

    Again, regarding diphenhydramine, there's very little comparative effectiveness research out there comparing the various agents. This NASA study was notable for their extensive list of comparisons – along with the highly entertaining modality of testing. Whether their provoked nausea stimulus is entirely generalizable to patients with acute vertigo is another matter, as well.

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