Cerenia’s anti-nausea effect lasts approximately 24 hours in cats, which is why it’s dosed once daily. The drug starts working within 1 to 2 hours after administration and maintains its effect through the rest of the day, giving most cats a full day of relief from vomiting and nausea per dose.
How Long the Effect Lasts
Cerenia (the brand name for maropitant citrate) works by blocking a specific receptor in the brain that triggers vomiting. In cats, the injectable form is dosed once every 24 hours, and research supports that the anti-nausea effect holds for that full window. The drug’s biological half-life in cats is 13 to 17 hours, meaning it takes that long for the body to clear just half the dose. Enough active drug remains in the system to suppress nausea for a full day.
Studies have also shown that when given orally (which is technically off-label in cats, since only the injectable form is approved for feline use), maropitant still provided strong anti-vomiting protection even when administered 18 hours before an event known to cause nausea. This further confirms the drug’s long working window.
How Quickly It Kicks In
You can expect Cerenia to start working within about 1 to 2 hours of administration. If your cat receives an injection at the vet’s office, the onset may be slightly faster than with an oral dose, but either way, improvement in nausea and vomiting typically follows within that first couple of hours. For motion sickness, this means giving it at least an hour or two before a car ride for the best protection.
Injectable vs. Oral Dosing
Cerenia is officially approved for cats only as an injectable solution, given under the skin (subcutaneously) or into a vein at a dose of 1 mg per kilogram of body weight. Your vet may administer this in the clinic, or in some cases send you home with oral tablets to give off-label. The oral dose used in research for cats has been higher, around 2.5 mg/kg, because oral absorption differs from injection.
Regardless of the form, the once-daily dosing schedule stays the same. Cerenia can be given for up to 5 consecutive days when used as an injectable. If your vet prescribes it for longer or in tablet form, they’ve made that decision based on your cat’s specific situation.
How Long It Takes to Fully Leave the Body
With a half-life of 13 to 17 hours, Cerenia is mostly cleared from a cat’s system within about 2 to 3 days after the last dose. The body eliminates it through the liver at a rate of roughly 4.6 mL per minute per kilogram of body weight, which is relatively fast clearance. For cats with liver problems, the drug may linger longer since the liver is responsible for breaking it down. Your vet may adjust dosing or choose a different medication in those cases.
Age Restrictions for Kittens
Cerenia’s safety has not been established in kittens younger than 16 weeks of age. The European Medicines Agency notes that vets should weigh the risks and benefits before using it in younger kittens or in pregnant or nursing cats. There’s no specific minimum weight requirement listed in the product guidelines; dosing is simply calculated by body weight at 1 mg/kg.
Common Side Effects
Most cats tolerate Cerenia well. The most commonly reported side effects are mild and short-lived: pain or irritation at the injection site, drooling, and temporary drowsiness. Some cats may seem quieter than usual for a few hours after receiving the drug, which can be hard to distinguish from the effects of whatever illness prompted the prescription in the first place. These side effects generally resolve on their own well before the next dose is due.
One thing worth noting: Cerenia controls nausea and vomiting, but it doesn’t treat the underlying cause. If your cat is vomiting because of kidney disease, a foreign object, or an infection, the vomiting may return once the drug wears off unless the root problem is also addressed. Cerenia buys comfort and time, but it isn’t a cure on its own.