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By Wendy C. Brooks, DVM, DipABVP
Educational Director,

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Meclizine Hydrochloride (Bonine, Antivert, Dramamine, UniVert, Vertin-21)

Brand Names: Bonine, Antivert, Dramamine Less Drowsy Formula, UniVert, Vertin-21

Available in 12.5 mg, 25 mg and 32 mg tablets


Motion sickness is an important problem for many pets and while there are several medications with an ability to relieve the discomfort and nausea associated with motion sickness, each has pros and cons. Sometimes sedation is desired for the travel period and sometimes it is not. Acepromazine, for example, lasts for 6 to 8 hours but is very sedating. Some medicines, such as maropitant, require an hour or more for their effect to kick in. Meclizine provides a relatively short-acting effect with minimal sedation and, even though it is a human medication, it has proved to be quite helpful for nausea relief associated with motion sickness.

How this Medication is Used

Meclizine hydrochloride is generally used for nausea relief due to motion sickness. It is also used to control the nausea resulting from vestibular disease, a syndrome characterized by vertigo and loss of balance.

To prevent motion sickness, meclizine hydrochloride should be given approximately 30 minutes before travel. Anti-nausea effects can be expected to last approximately 6 hours. Meclizine hydrochloride can be given with or without food.  

If a dose is accidentally skipped, do not double up on the next dose. Simply give the medication when it is remembered and be sure to wait at least 6-8 hours before the next dose.

Side Effects

Meclizine hydrochloride is a member of the piperazine class of antihistamines. It may produce some drowsiness though nothing like the six to eight hours of tranquilization yielded by its cousin acepromazine.

Most antihistamines have potential to cause any of a group of symptoms referred to as anticholinergic symptoms: urinary retention, dry mouth, increased heart rate, and exacerbation of glaucoma (elevated pressure within the eye). It may also reduce the ability to produce milk in lactating mothers.

Interactions with other Drugs

Meclizine hydrochloride should not be given in conjunction with other tranquilizing drugs as such a combination may lead to excess sedation. Similarly, it should not be given in conjunction with other antihistamines so as to minimize the potential for the unpleasant side effects listed above.

Concerns and Cautions

  • Meclizine hydrochloride is known to cause birth defects in experimental animals and thus should not be used in pregnant pets.
  • Due to its potential to reduce milk production, meclizine hydrochloride should not be given to nursing mothers.
  • Meclizine hydrochloride should not be given to patients who are at risk for urinary retention (prostate enlargement, spinal disease, etc.).
  • Meclizine hydrochloride should not be given to patients with a history of heart failure.
  • Meclizine hydrochloride use may interfere with allergic skin testing in patients undergoing evaluation for airborne allergies.
  • Meclizine hydrochloride activity can be expected to be prolonged in patients with liver disease.
  • Patients who do not tolerate meclizine hydrochloride might do better with maropitant citrate, an antinausea medication developed and labeled for the treatment of motion sickness in pets.

It is our policy not to give dosing information over the Internet.


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