Let’s spend a few weeks talking about meclizine. Most patients complaining of dizziness or vertigo have been given a prescription for meclizine at some point. For a medication that is so widely used, there is very little solid information or recent research to back this up.
Meclizine goes by a few names; meclizine is the generic term, but it is also packaged under the names Antivert, Bonine, and Dramamine II. The original Dramamine (I guess we will call it Dramamine I) is a similar medication called Dimenhydrinate. Dramamine II is marketed as the “less drowsy” formula, although I am unaware of any studies to substantiate that claim. In fact one study showed that dimenhydrinate caused drowsiness for a shorter period of time than did meclizine.
So many patients come in to our balance clinic having received a prescription for meclizine, 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.’ Most do not have a clear understanding of the purpose or potential benefit or negative effects of taking meclizine.
Most patients nod their head in agreement if I comment that they probably would not have come to my clinic if the meclizine resolved their symptoms. Most agree that the only thing they noticed was that the meclizine made them sleepy. Most are surprised when I tell them that meclizine does not actually treat inner ear disease, that it won’t keep them for getting dizzy, lightheaded or off balance, and they won’t get better any faster by taking it.
According to Drugs.com, the mechanism of action is described as:
“Antiemetic; antivertigo agent—The mechanism by which meclizine exerts its antiemetic, anti–motion sickness, and antivertigo effects is not precisely known but may be related to its central anticholinergic actions. It diminishes vestibular stimulation and depresses labyrinthine function. An action on the medullary chemoreceptive trigger zone may also be involved in the antiemetic effect.”
That doesn’t sound very convincing to me.
A recent 2012 study out of Belgium does support that meclizine probably has a sedating effect on the gain of the vestibular-ocular reflex, suspected to be a ‘central action on the medial vestibular nucleus’.
So, how shall we interpret that information as it relates to someone complaining of dizziness? First, and I have talked about this at length on this blog, you have to be more specific in your complaints. The term “dizziness” is very vague and can mean many different things. Some complaints of dizziness can be helped by a temporary prescription of meclizine, many won’t be affected at all, and some could be made worse.
Basically, if your inner ear is making you sick, and by sick I mean nauseous, then there is a role for meclizine. It will help relieve the temporary but acute vertigo and nausea associated with a few specific inner ear conditions such as Meniere’s disease or vestibular neuritis. It will also help relieve the nausea associated with motion sickness. It does this by reducing the information received by the brain from the inner ear. In an acute inner ear disease situation, what is making you spin and sick 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.
As we have recently discussed with motion sickness, reducing the information from the inner ear reduces the conflict between vestibular and visual information. So, in these two situations, meclizine can be helpful.
Next week, I am going to recycle an article that I wrote many years ago with my colleague, Dr. Brian Collie. Dr. Collie is an ENT specialist and a registered pharmacist. It is about 15 years old and is no longer available on the web, so I hope you find it interesting. I will update the article where it is needed.