Very few pain medications are safe for cats, and none of the common over-the-counter painkillers in your medicine cabinet should ever be given to them. Cats lack key liver enzymes that humans and even dogs rely on to break down these drugs, which means medications like acetaminophen (Tylenol), ibuprofen (Advil), and aspirin can cause organ failure or death at surprisingly small doses. Safe pain relief for cats exists, but it almost always requires a veterinarian’s involvement.
Why Most Human Painkillers Are Toxic to Cats
The root of the problem is in your cat’s liver. Cats are missing specific enzymes called UGT1A6 and UGT1A9, which are responsible for a process called glucuronidation. This is the main way mammals metabolize and clear painkillers from the body. Without these enzymes, drugs that are routine for humans build up to dangerous concentrations in a cat’s bloodstream.
Acetaminophen is the most dangerous. A single regular-strength capsule (325 mg) can cause severe toxicity in a cat, triggering vomiting, depression, and a condition where the blood can no longer carry oxygen properly. Cats also lack a second enzyme (N-acetyltransferase 2), which compounds the problem. There is no safe dose of acetaminophen for cats.
Ibuprofen damages the stomach lining and kidneys, and cats are susceptible at roughly half the dose that would harm a dog. Aspirin lingers in a cat’s system for an unusually long time because of the same enzyme deficiency. Its half-life in cats is 37.5 hours, compared to about 6 hours in dogs. Even doses as low as 5 mg have caused adverse effects in cats. Aspirin toxicity can progress from vomiting and weakness to stomach ulceration, liver damage, seizures, and coma.
FDA-Approved Pain Medications for Cats
Only two anti-inflammatory drugs (NSAIDs) are FDA-approved for use in cats, and both are limited to short-term pain control after surgery such as spaying, neutering, or orthopedic procedures.
- Meloxicam is approved as a single injection given under the skin before surgery. In the United States, it is not approved for repeated dosing in cats. More than one dose can cause kidney failure and death.
- Robenacoxib (brand name Onsior) is approved for up to three days of use, given as either a tablet or an injection. More than three doses have not been shown to be safe.
No NSAIDs are currently approved for long-term use in cats in the United States. This is a significant gap, because many cats develop chronic conditions like osteoarthritis as they age. Veterinarians sometimes prescribe NSAIDs off-label for longer periods under careful monitoring, and 2024 guidelines from the International Society of Feline Medicine and the American Association of Feline Practitioners now offer vets a framework for doing this more safely. If your cat is on an NSAID for more than a few days, expect your vet to require blood and urine tests before starting treatment and at regular intervals afterward.
Side effects of NSAIDs in cats include vomiting, diarrhea, loss of appetite, and lethargy. Serious reactions can include stomach ulcers, kidney damage, and liver problems. Cats that are dehydrated, have existing kidney or liver disease, or are taking corticosteroids face higher risk and generally should not take NSAIDs.
Other Prescription Options for Cat Pain
Because NSAID options are so limited, veterinarians often turn to other drug classes for managing pain in cats, especially chronic pain from arthritis or cancer.
Buprenorphine is an opioid pain reliever commonly used in cats. It can be given by injection at a clinic, but for home use it is often administered inside the cheek (buccally), where it absorbs through the oral lining. This makes it one of the more practical prescription painkillers for cat owners to give at home. It is typically dosed every 6 to 8 hours.
Gabapentin is widely used for chronic pain in cats and also helps with anxiety. It is given by mouth, usually every 8 to 12 hours. Many cat owners recognize gabapentin as the medication their vet recommends before stressful car rides or vet visits, but at higher or more frequent doses it serves as a genuine pain management tool. Sedation is the most common side effect, particularly when cats first start taking it.
Monthly Injections for Arthritis Pain
One of the biggest recent advances in feline pain management is Solensia (frunevetmab), an FDA-approved monthly injection for osteoarthritis pain in cats. It works differently from traditional painkillers. Instead of blocking inflammation broadly, it targets a specific protein called nerve growth factor that drives pain signaling in damaged joints. By neutralizing this protein, it reduces pain perception without passing through the liver the way NSAIDs do.
In clinical trials, cats receiving Solensia showed steady improvement over time. By day 56 of one study, 80% of treated cats showed meaningful pain relief as assessed by their owners, compared to 47% of cats receiving a placebo. A larger confirmatory study found 76.5% success at day 84 versus 67.3% for placebo. The injection is given once a month at your vet’s office, which eliminates the challenge of giving a cat daily pills.
Solensia is specifically designed for long-term use, filling the gap left by NSAIDs. It has become a first-line option for many vets treating older cats with joint pain.
How to Tell if Your Cat Is in Pain
Cats are notoriously good at hiding pain, which is one reason it often goes untreated. A validated tool called the Feline Grimace Scale can help you recognize discomfort by looking at five specific facial features: ear position, how open or squinted the eyes are, tension around the muzzle, whisker position, and head position. Each is scored from 0 to 2, with a total score of 4 or higher (out of 10) indicating the cat is in enough pain to need treatment.
In practical terms, a cat in pain often has ears flattened and rotated outward, squinted eyes, a tense or elliptical muzzle shape, and whiskers pushed straight forward rather than relaxed and curved. You might also notice decreased grooming, reluctance to jump, hiding, reduced appetite, or uncharacteristic aggression when touched. Subtle changes in litter box habits or a cat that stops using elevated resting spots can also signal joint pain, particularly in older cats.
What You Can Safely Do at Home
There is no over-the-counter pain medication you can safely give a cat without veterinary guidance. The safest immediate steps if you suspect your cat is in pain are to keep them warm, quiet, and comfortable while you arrange a vet visit. For cats with known arthritis, non-drug approaches like heated beds, low-entry litter boxes, ramps to favorite perches, and maintaining a healthy weight all reduce the load on painful joints.
If your vet has prescribed a medication, give it exactly as directed. Never split a dog’s NSAID prescription with a cat, even if the drug name is the same. The dosing, formulation, and safety profile differ dramatically between species. And never repeat a dose of any painkiller without explicit instructions, since the margin between a therapeutic and a toxic dose in cats is extremely narrow.