Prednisone is not the best choice for cats, but a closely related drug called prednisolone is widely used and generally safe when prescribed by a veterinarian. The distinction matters: cats have difficulty converting prednisone into its active form, so they absorb roughly four times less of the drug compared to prednisolone. Most vets will prescribe prednisolone specifically for this reason, and if your cat’s prescription says “prednisone,” it’s worth confirming with your vet that they meant prednisolone.
Why Cats Need Prednisolone, Not Prednisone
Prednisone is a prodrug, meaning the body has to convert it into prednisolone before it actually works. This conversion happens in the liver. Dogs handle this step reasonably well, though even in dogs prednisone has only about 65% of the bioavailability of prednisolone. Cats are significantly worse at it. A study measuring blood levels after a single oral dose found that prednisolone produced roughly four times higher plasma concentrations than the same dose of prednisone. In practical terms, giving a cat prednisone means much of the drug passes through without doing its job.
This is why prednisolone is the standard corticosteroid for cats. If you see “prednisone” and “cats” used interchangeably online, the intended drug is almost always prednisolone.
What Prednisolone Treats in Cats
Prednisolone is one of the most commonly prescribed medications in feline medicine. It reduces inflammation and suppresses overactive immune responses, making it useful for a wide range of conditions. The most frequent uses include feline asthma, inflammatory bowel disease (IBD), allergic skin conditions, and certain autoimmune disorders.
For IBD in particular, prednisolone is so closely associated with treatment that it’s considered a first-line therapy. Many cats with small intestinal IBD respond well to it. Typical doses range from about 1 to 2 mg/kg per day depending on the condition and severity, though your vet will tailor the dose to your cat’s specific needs and body weight.
Common Short-Term Side Effects
Most cats tolerate prednisolone well in the short term, but you’ll likely notice some changes. Increased hunger is the most obvious one. Your cat may act ravenous, beg for food, or seem unsatisfied after meals. Increased thirst and more frequent urination are also common, so you may find yourself refilling the water bowl and cleaning the litter box more often.
Some cats become less energetic or seem a bit sluggish. One side effect that’s more specific to cats is the unmasking of hidden infections, particularly upper respiratory infections. The immune suppression from steroids can allow a dormant infection to flare up, so watch for sneezing, nasal discharge, or eye irritation that wasn’t there before starting the medication.
Long-Term Risks to Know About
The more serious concerns arise with prolonged use. The two biggest risks for cats on corticosteroids are steroid-induced diabetes and steroid-induced congestive heart failure. A large study of over 1,000 cats receiving a corticosteroid found that 3.83% developed steroid-induced diabetes and 0.82% developed steroid-induced congestive heart failure. Those numbers are relatively low, and notably, the risk did not increase with repeated doses in that study.
Still, about 1 in 26 cats developing diabetes is not trivial, especially for cats that already carry risk factors like obesity or a sedentary lifestyle. Steroid-induced diabetes in cats can sometimes be reversible if the steroid is discontinued in time, but it can also become permanent. Signs to watch for include excessive drinking, frequent urination beyond what the steroid itself causes, weight loss despite a good appetite, and lethargy.
Cats with undiagnosed heart disease face additional risk. Even a small percentage developing congestive heart failure means that cats with known or suspected heart conditions need careful evaluation before starting steroids. Corticosteroids promote fluid retention, which can push a borderline heart into failure.
Dangerous Drug Combinations
One combination to be particularly cautious about is corticosteroids with NSAIDs (nonsteroidal anti-inflammatory drugs like meloxicam). Both drug classes independently carry risks for the gastrointestinal tract, kidneys, and blood clotting. Used together, the risk of GI ulceration and perforation rises significantly. Perforation can lead to life-threatening infection in the abdomen. This combination is generally considered contraindicated in cats, and clinical experience suggests cats are more susceptible to kidney damage from these drugs than dogs are. If your cat is on any pain medication, make sure your vet knows before adding prednisolone.
Why You Can’t Stop Steroids Suddenly
When a cat takes prednisolone daily for more than two to three weeks at doses above a minimal threshold, the body’s natural cortisol production shuts down. The adrenal glands essentially go dormant because the medication is doing their job for them. If you stop the drug abruptly, the adrenal glands can’t ramp back up quickly enough, and your cat can develop a dangerous cortisol deficiency, similar to a condition called hypoadrenocorticism.
This is why tapering is essential. The typical approach involves reducing the dose by 10% to 25% at a time, then holding at the new dose for one to four weeks before reducing again. The speed of tapering depends on how long your cat has been on the medication. A cat that’s been on steroids for less than two to three months can usually taper faster, while a cat on long-term therapy needs a slower, more cautious reduction. Your vet will guide the schedule based on your cat’s condition, but the key rule is simple: never stop prednisolone cold turkey.
Monitoring During Treatment
Cats on long-term prednisolone need regular veterinary check-ins. Your vet will watch for clinical signs of overtreatment or complications, including changes in appetite, activity level, weight, and drinking or urination patterns. Blood glucose monitoring is important given the diabetes risk, and periodic bloodwork helps catch problems before they become serious.
At home, you play a role in monitoring too. Keep track of how much water your cat drinks, how often the litter box needs changing, and any shifts in energy or behavior. Weight changes in either direction are worth reporting. If your cat starts drinking dramatically more water than usual or loses weight despite eating well, those are signals that something may need adjusting.
Is It Safe Overall?
Prednisolone is safe for most cats when used appropriately, meaning the right drug (prednisolone, not prednisone), the right dose, and proper tapering when it’s time to stop. It’s been a cornerstone of feline medicine for decades precisely because it works well and most cats tolerate it. The risks are real but manageable with veterinary oversight. For conditions like asthma or IBD, where the alternative is a cat that can’t breathe comfortably or absorb nutrients, the benefits typically outweigh the risks by a wide margin. The cats most likely to run into trouble are those with pre-existing diabetes risk, undiagnosed heart disease, or those kept on high doses longer than necessary without monitoring.