# Cerenia and Restlessness in Cats: Side Effects Yes, restlessness is a possible side effect of Cerenia (maropitant) in cats, though it is not the most common reaction owners report. Most cats tolerate the drug well, and the benefits for vomiting and nausea often outweigh the risks. Still, any change in your cat's behavior after a dose deserves attention. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Restlessness, pacing, and unusual agitation can happen after Cerenia, but they are uncommon compared with drowsiness and drooling. - Cerenia is FDA-approved for vomiting in cats and is widely used for nausea, motion sickness, and pre-surgery vomiting prevention. - Never adjust the dose yourself. Your veterinarian calculates the dose from your cat's weight and health status. - A single odd episode that fades within a few hours is usually not an emergency, but repeated or worsening signs need a call. - Call your vet the same day if restlessness comes with vomiting that will not stop, tremors, wobbling, or trouble breathing. ## What Is Cerenia and What Do Veterinarians Use It For? Cerenia is the brand name for maropitant citrate, a prescription antiemetic labeled for treating vomiting in dogs and cats [1]. It comes as tablets and as an injectable solution, and it is one of the most commonly prescribed anti-nausea drugs in small animal practice. Veterinarians use Cerenia for several situations: - Acute vomiting from a stomach upset, dietary indiscretion, or infection - Nausea and vomiting after surgery or anesthesia - Motion sickness during car travel - Chronic vomiting tied to kidney disease, pancreatitis, or other long-term conditions - Nausea that makes a cat stop eating Cerenia is also sometimes given by other routes when pills and injections are hard to manage. One small study of eight cats used a compounded transdermal form applied to the inner ear at 4 mg per cat once daily for five days and found an antiemetic effect [2]. That form is compounded by a pharmacy, not sold as a standard product, and it is not the same as the FDA-approved tablet or injection. If your cat is on other medications, it helps to understand how different drugs affect behavior. Our guide to [gabapentin side effects in cats](/knowledge/veterinary-medicine/pet-medication-guide/gabapentin-side-effects-cats) covers another drug that can change how a cat acts. ## How Maropitant Works in the Body Maropitant is a neurokinin-1 (NK-1) receptor antagonist [1]. In plain terms, it blocks a specific receptor in the brain and gut that triggers the vomiting reflex. By blocking that signal, it stops nausea and vomiting before they start. Because it works on the nervous system, it can produce behavioral effects in some cats. That is one reason a cat might seem sleepy, quiet, or occasionally restless after a dose. The drug also slows the muscular waves that move food through the stomach and intestine. In a study of healthy adult dogs, maropitant significantly decreased the rate of peristalsis in the stomach and jejunum, though it did not change intestinal diameter or wall thickness [1]. This slowing effect is part of why the drug works, but it can also explain why some pets seem off for a while. ## Dosing Basics for Cats Your veterinarian decides the dose. It is based on your cat's body weight, the reason for treatment, and your cat's overall health. Do not split, crush, or guess at a dose on your own. Cerenia for cats is typically given as a tablet by mouth or as an injection under the skin at the clinic. The injectable form is often used when a cat is actively vomiting and cannot keep a pill down. If your cat is hard to pill, ask your vet about the best option for your situation. For a missed dose, the general rule is to give it when you remember, unless it is almost time for the next dose. In that case, skip the missed dose and go back to the regular schedule. Never double up to make up for a missed dose. If you are unsure, call your veterinary clinic for guidance. ## Cerenia Side Effects in Cats: Common and Serious Most side effects are mild and short-lived. The table below lists what owners most often see and what to do about each one. | Side effect | How common or serious | What to do | |---|---|---| | Sleepiness or sedation | Common, mild | Let your cat rest. It usually fades within hours. | | Drooling or lip smacking | Common with tablets, mild | Offer water. It often stops on its own. | | Vomiting right after the pill | Uncommon, mild | Call your vet. The dose may not have been absorbed. | | Restlessness, pacing, agitation | Uncommon, usually mild | Watch closely. Call your vet if it lasts or worsens. | | Loss of appetite | Uncommon, mild | Monitor eating and drinking. Call if it lasts more than a day. | | Swelling, hives, or facial swelling | Rare, serious | This is an emergency. Go to a vet right away. | | Tremors, wobbling, or collapse | Rare, serious | This is an emergency. Seek care immediately. | | Trouble breathing | Rare, serious | This is an emergency. Seek care immediately. | Restlessness is the side effect many owners search for, and it does appear in some cats. A cat that paces, cannot settle, or seems agitated after a dose may be reacting to the medication. In most cases the behavior is brief. If your cat is genuinely distressed, panting, or cannot rest at all, treat it as a reason to call. Some behavior changes have nothing to do with the drug. Stress from a vet visit, a car ride, or an underlying illness can all make a cat restless. If your cat is overgrooming or showing other stress behaviors, our article on [psychogenic overgrooming in cats](/knowledge/veterinary-medicine/behavior/psychogenic-overgrooming-in-cats-stress-induced-alopecia-vs-flea-allergies) explains how stress and skin problems can overlap. ## Is Cerenia Safe for Cats? Cerenia is considered safe for most cats when it is used as directed by a veterinarian. It has been studied in controlled settings, and the evidence supports its use for vomiting. A meta-analysis of five controlled feline studies found that emesis occurred in 11 of 141 cats given maropitant compared with 70 of 152 controls, a meaningful reduction in vomiting risk [3]. That is a strong signal that the drug does what it is meant to do. Safety does not mean no side effects. It means the benefits are usually worth the risks for the right patient. Your vet weighs your cat's age, weight, kidney and liver function, and other medications before prescribing. If your cat takes other drugs, ask about interactions. Our guide to [seizure medication side effects in cats](/knowledge/veterinary-medicine/pet-medication-guide/seizure-medication-side-effects-cats) is a useful starting point for understanding how multiple medications can affect behavior. ## Who Should Not Take Cerenia and What Interacts With It Cerenia is not right for every cat. Tell your veterinarian about your cat's full medical history before starting treatment. Cats that may need extra caution include: - Cats with liver disease, since the drug is processed by the liver - Very young kittens, because dosing and safety are not well established in this group - Pregnant or nursing cats, unless your vet decides the benefit outweighs the risk - Cats with a known allergy to maropitant or similar drugs Drug interactions matter too. Because Cerenia can slow stomach and intestinal movement [1], it may affect how other oral medications are absorbed. If your cat takes multiple drugs, your vet may adjust timing or doses. Always give your vet a complete list of everything your cat receives, including prescriptions, over-the-counter products, and supplements. Do not start a new medication without checking first. ## Cerenia Injection in Cats The injectable form is common in clinics, especially when a cat is too nauseated to swallow a pill. It is given under the skin, usually once daily, and it starts working quickly. Owners sometimes ask whether the injection causes more restlessness than the tablet. There is no clear evidence that one form causes more behavioral side effects than the other. What matters is the total dose and your cat's individual response. If your cat had a reaction to an injection at the clinic, tell your vet before the next dose so the plan can be adjusted. ## Overdose and When to Call a Veterinarian or Poison Control If you think your cat received too much Cerenia, call for help right away. Do not wait for symptoms to appear. - ASPCA Animal Poison Control Center: (888) 426-4435 - Pet Poison Helpline: (855) 764-7661 Have your cat's weight, the strength of the medication, and the amount given ready when you call. These services may charge a consultation fee. Signs of a serious reaction include severe restlessness that will not stop, tremors, wobbling, collapse, vomiting that continues after treatment, swelling of the face or paws, and difficulty breathing. Any of these means emergency care, not a wait-and-see approach. ## Limitations and When to Contact a Veterinarian No article can tell you what is happening with your specific cat. Individual cases need a veterinarian who can examine your pet, review the history, and decide on next steps. Use these timing guidelines: **Call the same day** if your cat is restless and cannot settle, is pacing or panting, refuses food or water for more than a day, or vomits after taking the pill. **Go to an emergency clinic now** if you see facial swelling, hives, trouble breathing, tremors, collapse, or repeated unproductive vomiting. **Schedule a routine visit** if the restlessness is mild but keeps coming back after each dose, or if you have questions about whether to continue the medication. Keep a simple log of when you give the dose and what you observe afterward. That record helps your vet decide whether the drug is the cause or whether something else is going on. ## Frequently Asked Questions ### Can Cerenia cause restlessness in cats? Yes, restlessness is a possible side effect, though it is less common than drowsiness or drooling. Most reactions are mild and fade within hours. If your cat is pacing, agitated, or cannot settle, call your veterinarian for advice. ### How long do Cerenia side effects last in cats? Most mild side effects ease within a few hours to a day after a dose. If signs last longer or get worse, that is a reason to call your vet. Your cat's age, weight, and overall health can affect how long the drug stays active. ### Is Cerenia safe for cats long term? Cerenia is often used for short courses, and longer use is decided case by case by your veterinarian. Your vet will weigh the benefit of controlling vomiting against any risks. Regular checkups and bloodwork may be recommended during extended treatment. ### What should I do if my cat seems agitated after a Cerenia injection? Keep your cat in a quiet, safe space and watch closely. Call the clinic that gave the injection and describe what you see. If there is swelling, trouble breathing, tremors, or collapse, go to an emergency clinic right away. ### Can I stop giving Cerenia on my own? Do not stop a prescribed medication without talking to your veterinarian first. Stopping suddenly may bring back the vomiting or nausea the drug was controlling. Your vet can adjust the dose, switch drugs, or taper the plan safely. ## Related Articles - [What Are the Side Effects of Apoquel for Cats?](/knowledge/veterinary-medicine/pet-medication-guide/apoquel-side-effects-cats) - [What Are the Side Effects of Seizure Medication in Cats?](/knowledge/veterinary-medicine/pet-medication-guide/seizure-medication-side-effects-cats) - [What Are the Side Effects of Gabapentin for Cats?](/knowledge/veterinary-medicine/pet-medication-guide/gabapentin-side-effects-cats) - [Psychogenic Overgrooming in Cats: Stress-Induced Alopecia vs Flea Allergies](/knowledge/veterinary-medicine/behavior/psychogenic-overgrooming-in-cats-stress-induced-alopecia-vs-flea-allergies) - [Cat Urinary Tract Infection Side Effects](/knowledge/veterinary-medicine/clinical-methods/cat-urinary-tract-infection-side-effects) - [Cat Allergy Medication Side Effects: What to Watch For](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/cat-allergy-medication-side-effects) - [Cerenia for Cats: Side Effects and Dosing Basics](/knowledge/veterinary-medicine/pet-medication-guide/cerenia-cats-side-effects-dosage) - [Restlessness in Cats: Causes and What It Means](/knowledge/veterinary-medicine/behavior/restlessness-cats-causes-meaning) - [Does Mirataz Cause Restlessness in Cats? Side Effects](/knowledge/veterinary-medicine/pet-medication-guide/mirataz-restlessness-cats) ## References 1. [Maropitant Citrate Administration Significantly Decreases the Rate of Peristalsis in the Stomach and Jejunum and Does Not Significantly Alter Intestinal Diameter or Intestinal Wall Thickness in Healthy Adult Dogs](https://pubmed.ncbi.nlm.nih.gov/42083426/). Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association, 2026. 2. [Evaluation of the efficacy of transdermal administration of maropitant in managing vomiting in cats](https://pubmed.ncbi.nlm.nih.gov/36589400/). Open veterinary journal, 2022. 3. [Receptor-Targeted Antiemetic Strategies in Cats: A Systematic Review and Intervention-Specific Meta-Analysis](https://pubmed.ncbi.nlm.nih.gov/42599757/). Veterinary medicine and science, 2026. ## Further Reading - [American Veterinary Medical Association: First Aid Tips for Pet Owners](https://www.avma.org/resources-tools/pet-owners/emergencycare/first-aid-tips-pet-owners) - [Merck Veterinary Manual: Cat Owners](https://www.merckvetmanual.com/cat-owners) - [Cornell Feline Health Center: Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information)