# Keppra Side Effects in Cats: What Owners Should Watch For Most cats on Keppra (levetiracetam) get sleepy or a little unsteady in the first days, and those effects often ease as the body adjusts. Serious problems are uncommon but real, so knowing what is normal and what is not matters when you are giving keppra for cats side effects at home. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Sleepiness, mild wobbliness, and a temporary drop in appetite are the side effects owners report most often in the first days of treatment. - Never change or stop the dose on your own, because sudden withdrawal can trigger seizures. Call your veterinarian first. - Give the missed dose only if your veterinarian tells you to. Do not double up to catch up. - Call your vet the same day if your cat cannot walk, vomits repeatedly, or refuses food for more than 24 hours. - Go to an emergency clinic now if your cat has trouble breathing, collapses, or has a seizure that lasts longer than usual. ## What Keppra Is and Why Veterinarians Prescribe It Keppra is the brand name for levetiracetam, an anticonvulsant medication. In cats, veterinarians use it most often to help control seizures, either alone or alongside another seizure medication. It is also sometimes used for other conditions that involve abnormal electrical activity in the brain, and your veterinarian will explain the specific reason it was chosen for your cat. Keppra is not approved by the FDA for cats, so any use in cats is extra-label. That is common in veterinary medicine and does not mean the drug is unsafe. It means your veterinarian is using clinical judgment and experience to pick a medication that fits your cat's problem. Seizure control in cats often involves more than one drug, and side effects can overlap between them. If your cat takes other anticonvulsants, ask your veterinarian which symptoms belong to which medication. Our guide to [seizure medication side effects in cats](/knowledge/veterinary-medicine/pet-medication-guide/seizure-medication-side-effects-cats) walks through the broader picture. ## How Keppra Works in Cats Levetiracetam works differently from older seizure drugs. It binds to a specific protein in the brain that helps regulate how nerve cells release signaling chemicals. By calming that release, it lowers the chance that a group of brain cells will fire in the runaway pattern that produces a seizure. This mechanism is one reason veterinarians like it. Many sedating drugs used in cats act on the GABA system, the same pathway targeted by gabapentin, benzodiazepines, and several anesthetics [1]. Keppra largely avoids that pathway, so it tends to cause less heavy sedation than some alternatives. That said, mild sleepiness still happens, especially at the start. Keppra also clears from the body fairly quickly, which is why it is often given two or three times a day. If you miss doses, blood levels drop and seizure protection weakens. ## Dosing Basics for Cats Your veterinarian calculates the dose from your cat's weight, kidney function, seizure pattern, and other medications. There is no single dose that fits every cat, so follow the label exactly and do not adjust it based on how your cat looks that day. Keppra comes as tablets and as a liquid. Some cats take the liquid more easily, and some pharmacies can compound a flavored version. Ask your veterinarian before switching between forms, because absorption can differ. ### What to do about a missed dose If you miss a dose, call your veterinarian's office for instructions. In general, a dose given a few hours late is better than a skipped dose, but a dose given too close to the next one can push blood levels too high. Never give two doses at once to make up for a missed one. ### What to do if your cat vomits a dose Do not repeat the dose unless your veterinarian tells you to. You cannot know how much was absorbed. Note the time of the vomit and call the clinic. ## Common and Serious Side Effects of Keppra for Cats The table below separates the effects owners see most often from the ones that need a phone call or a trip to the clinic. Severity can shift over the first week, so keep watching even if day one looks fine. | Side effect | How common or serious | What to do | |---|---|---| | Sleepiness, quiet behavior | Common and usually mild, most noticeable in the first days | Let your cat rest. Call your vet if your cat is hard to wake or will not respond to you | | Wobbliness, unsteady walking | Common at the start, often improves as the body adjusts | Keep your cat away from stairs and high furniture. Call your vet if walking does not improve or gets worse | | Appetite loss | Common and often short lived | Offer small, warm, smelly meals. Call your vet if your cat eats nothing for 24 hours | | Vomiting or drooling | Less common, sometimes linked to the taste of the liquid | Call your vet. Do not repeat a vomited dose on your own | | Agitation, pacing, unusual vocalizing | Uncommon | Call your vet the same day. This can be a sign the dose is too high for your cat | | Trouble breathing, collapse, severe weakness | Rare but serious | Go to an emergency clinic now | | Severe skin reaction (hives, facial swelling) | Rare but serious | Go to an emergency clinic now | Sedation is the effect owners notice first, and it is also the one most studied in cats. In a review of oral sedative and anxiolytic medications in cats, sedation scores varied widely between drugs and between individual cats, and palatability affected whether cats would take a medication at all [1]. That variability is why two cats on the same drug can look very different. Wobbliness deserves special attention in cats with kidney disease. A study of cats with chronic kidney disease found that sedation did not significantly change kidney function markers like SDMA and creatinine at the point of maximum sedation or two hours later [2]. That is reassuring for short sedation events, but it does not mean long-term anticonvulsant use is risk-free for a cat with kidney problems. Your veterinarian will monitor bloodwork over time. If your cat takes other medications for itching or allergies, side effects can stack up. Our articles on [gabapentin side effects in cats](/knowledge/veterinary-medicine/pet-medication-guide/gabapentin-side-effects-cats) and [cat allergy medication side effects](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/cat-allergy-medication-side-effects) cover the sedation and appetite changes those drugs can add. ### Effects that usually settle Mild sleepiness, a soft wobble, and a day or two of picky eating are the classic early effects. Many cats look close to normal within a week or two. If your cat seems comfortable, eating most meals, and using the litter box, you can usually watch and wait while staying in touch with your clinic. ### Effects that do not settle If sleepiness deepens instead of fading, or if your cat stops walking steadily after the first week, that is not a normal adjustment pattern. Call your veterinarian. Dose changes are common and often solve the problem quickly. ## Who Should Not Take Keppra and What Interacts With It Cats with known hypersensitivity to levetiracetam should not take it. Cats with significant kidney disease need careful dosing because the drug clears through the kidneys, and your veterinarian may adjust the amount or the schedule. Tell your veterinarian about every medication, supplement, and topical product your cat receives. Drug interaction information specific to cats is not well established in veterinary research, so your veterinarian will weigh each combination individually. Do not assume a product is safe because it is sold without a prescription. Pregnancy and nursing status matter too. If your cat is pregnant or nursing, tell your veterinarian before starting or continuing the medication. ## Overdose and When to Call for Help If your cat gets extra doses, call your veterinarian or a pet poison hotline right away, even if your cat looks fine. Signs of too much medication can include heavy sedation, severe wobbliness, vomiting, and trouble staying awake. Two phone numbers you can use: - ASPCA Animal Poison Control Center: (888) 426-4435 - Pet Poison Helpline: (855) 764-7661 Have your cat's weight, the medication strength, and the approximate number of extra doses ready before you call. Do not wait for symptoms to appear. ## Limitations and When to Contact a Veterinarian Every cat responds differently, and only your veterinarian can judge your cat's specific situation. Use the timing below as a guide. **Call the same day if:** - Your cat refuses all food for more than 24 hours - Vomiting happens more than once or twice - Wobbliness makes walking difficult or your cat falls - Your cat seems agitated, paces, or vocalizes in a way that is new - You missed more than one dose and are unsure what to do **Go to an emergency clinic now if:** - Your cat has trouble breathing - Your cat collapses or cannot stand - A seizure lasts longer than your cat's usual seizures, or seizures cluster close together - You see hives, facial swelling, or sudden severe weakness **Bring up at your next routine visit:** - Mild sleepiness that is slowly improving - Appetite that is a little lower than usual but still present - Any question about timing, food, or how to give the medication ## Frequently Asked Questions ### How long do Keppra side effects last in cats? Most mild effects fade within one to two weeks as your cat adjusts. If sleepiness or wobbliness is still getting worse after that window, call your veterinarian. Some cats need a dose change to feel normal again. ### Can I stop Keppra suddenly if my cat seems fine? No. Stopping a seizure medication suddenly can trigger seizures, sometimes worse than before. Call your veterinarian before making any change, even if your cat has been seizure free for months. ### Does Keppra make cats aggressive? Aggression is not a typical effect, but behavior changes like agitation or unusual vocalizing can happen. If your cat acts differently in a way that worries you, call your veterinarian the same day. A dose adjustment often helps. ### Can I give Keppra with food? Yes, most cats can take it with or without food. If your cat vomits after an empty-stomach dose, try a small meal first. Ask your veterinarian whether food affects the specific form you were given. ### Is Keppra safer than phenobarbital for cats? They work differently and carry different risks, so there is no single answer. Keppra tends to cause less heavy sedation because it does not act mainly on the GABA pathway that many sedatives target. Your veterinarian picks based on your cat's seizures, bloodwork, and other health problems. ## Related Articles - [Cat Allergy Medication Side Effects: What to Watch For](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/cat-allergy-medication-side-effects) - [What Are the Side Effects of Gabapentin for Cats?](/knowledge/veterinary-medicine/pet-medication-guide/gabapentin-side-effects-cats) - [What Are the Side Effects of Apoquel for Cats?](/knowledge/veterinary-medicine/pet-medication-guide/apoquel-side-effects-cats) - [Cat Urinary Tract Infection Side Effects](/knowledge/veterinary-medicine/clinical-methods/cat-urinary-tract-infection-side-effects) - [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 Bravecto for Dogs? What to Watch For](/knowledge/veterinary-medicine/pet-medication-guide/bravecto-side-effects-dogs) - [Lactulose Side Effects in Cats: What to Expect and Watch For](/knowledge/veterinary-medicine/pet-medication-guide/lactulose-side-effects-in-cats) - [Albon Side Effects in Cats: What Owners Should Watch For](/knowledge/veterinary-medicine/pet-medication-guide/albon-side-effects-cats) - [Mirtazapine for Cats: Side Effects, Dosage, and Safety](/knowledge/veterinary-medicine/pet-medication-guide/mirtazapine-cats-side-effects-dosage) ## References 1. [Oral use of anxiolytic, sedative, and anaesthetic medications in domestic cats (Felis catus): A scoping review](https://pubmed.ncbi.nlm.nih.gov/42431357/). Veterinary journal (London, England : 1997), 2026. 2. [Short-term effect of sedation on kidney function markers in cats with chronic kidney disease](https://pubmed.ncbi.nlm.nih.gov/42208589/). American journal of veterinary research, 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) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)