Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066




(for veterinary information only)




16 mg, 24 mg, 60 mg, & 160 mg



While strong nausea-controlling drugs in injectable form have been available for dogs for some time, oral medications have been lacking. Until recently, efforts were largely confined to the oral use of metoclopramide (which is rather short acting) and meclizine (which is not approved for use in dogs). In 2008, Pfizer released maropitant citrate, a strong anti-nauseal medication for dogs that could be given once a day. Maropitant has since been approved for cats as well.

Vomiting occurs when the vomit center of the brain stem is stimulated. It may be stimulated a number of ways: directly (as in over-eating/over-filling the stomach), via emotional input (such as receiving shocking news), through "vestibular" input (such as motion sickness), via the chemoreceptor trigger zone in the brain stem (as when nauseating toxins are detected in the bloodstream) or a combination of any of the above. The ultimate result of all these unpleasant stimulation is triggering a brain area called the "vomit center." Once the vomit center is activated, well, you can guess the result.

An important molecular step in initiating vomiting, involves the binding of a material called “substance P” to a structure called the “NK-1 receptor.” This lock and key binding occurs in both the vomit center and in the chemoreceptor trigger zone. Maropitant citrate mimics the structure of substance P and binds the NK-1 receptors so that they cannot bind substance P thus making stimulation of the vomit center extremely difficult.

Substance P is involved in numerous inflammatory conditions which has led to further investigation of maropitant citrate uses far beyond nausea control. It is currently being explored in treatment of chronic upper respiratory infections in cats, cough suppression, feline idiopathic cystitis, and inflammatory bowel disease.



Maropitant is used once a day to control nausea. It can be given as a shot or as a tablet. The dose is higher for motion sickness versus for treatment of disease-related nausea. For the former, maropitant can be given two days in a row and for the latter for 5 days in a row. Originally, a 5 days on/one day off schedule was recommended for long term use but, now that maropitant has been out for many years, long term use has come to be more common without skipping days.



Side effects are uncommon with the use of this medication but the most commonly noted side effect is vomiting the pill immediately after administration. Giving the medication with a small amount of food can mitigate this.

The FDA has received sporadic reports of more serious reactions: facial swelling, incoordination, fever, muscle tremors, and convulsions.




The risk of experiencing the above maropitant side effects is increased when maropitant is combined with other drugs that are highly blood protein bound in the circulation. Common drugs that meet this criterion include non-steroidal anti-inflammatory drugs, sulfa class antibiotics, as well as others.

Some drugs use the same removal enzyme system as maropitant and concurrent use can decrease the effectiveness of maropitant. Such medications include: cimetidine (antacid), erythromycin (antibiotic), ketoconazole (antifungal), itraconazole (antifungal), terbinafine (antifungal), fluoxetine (for behavior modification).




  • Note that the dosage recommended for a one time control of motion sickness is much higher than that for longer term nausea relief (as in the treatment of a disease).
  • Maropitant is approved for puppies over 8 weeks of age and cats at least 16 weeks of age.
  • Do not give this medication wrapped in a treat that may upset your pet’s stomach. Minimize fatty treats as they work against the effectiveness of the medication.
  • Maropitant may require dose adjustment for pets with liver disease.
  • Maropitant has not been evaluated in pregnant or nursing animals.
  • Store maropitant tablets in their blister packs at room temperature.
  • If a dose is accidentally skipped, simply give it when it is remembered. Do not double up on the next dose.

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Page posted: 2/7/2012
Page last revised: 1/16/2021