CBD is generally well tolerated by cats at appropriate doses, but it is not without risks. A six-month clinical trial found that healthy cats given CBD daily at 4 mg/kg body weight showed no serious adverse effects over the entire study period. That said, CBD can cause mild liver enzyme changes, interacts with certain medications, and the unregulated market means product quality varies wildly. Here’s what you need to know before giving it to your cat.
What the Safety Studies Show
The most reassuring evidence comes from two randomized, blinded, placebo-controlled studies published in Frontiers in Veterinary Science. In the longer of the two, cats received a THC-free CBD oil at 4 mg/kg body weight every day for 26 weeks. The researchers concluded the CBD was “well tolerated” over that entire period, with no clinically significant health problems in the treatment group compared to placebo.
A separate pharmacokinetic study using a CBD-rich hemp paste found that cats did experience a statistically significant rise in ALT, a liver enzyme. The average increase was about 18 units per liter after one week of dosing. Importantly, all values stayed within the normal reference range (26 to 109 U/L), rising from an average of 66 to 84. Other liver markers like ALP and AST didn’t change. This pattern is different from dogs, where CBD tends to elevate ALP instead. The rise is mild, but it suggests that cats on CBD long-term should have periodic bloodwork to monitor liver function.
Common Side Effects
Data from the Merck Veterinary Manual paints a more cautious picture of what happens in real-world use, outside the controlled conditions of a clinical trial. Among reported CBD exposure cases in cats and dogs, 30% showed lethargy, 21% showed ataxia (unsteady, wobbly movement), and 6 to 7% experienced heightened sensitivity to touch, trembling, or urinary incontinence.
These numbers are higher than you’d expect from pure CBD alone. The Merck Manual attributes these reactions to two likely causes: the cat consumed a large volume of a hemp product that technically contains less than 0.3% THC but enough in total quantity to cause effects, or the product was contaminated with unlabeled THC, synthetic cannabinoids, or other compounds. This distinction matters. A well-made, lab-tested CBD product at an appropriate dose carries far less risk than a random hemp product grabbed off a shelf.
THC Is the Real Danger
Cats are more sensitive to THC than dogs, and THC toxicity can cause serious neurological symptoms. U.S. hemp standards allow up to 0.3% THC on a dry matter basis, which sounds negligible but can add up if a cat eats a large amount of product or if the manufacturer’s quality control is poor. Some products on the market have been found to contain more THC than their labels claim.
Signs of THC toxicity in cats include pronounced sedation, disorientation, dilated pupils, low heart rate, and sometimes vomiting. If your cat shows any of these signs after consuming a CBD product, treat it as a potential THC exposure. The safest approach is to choose products specifically labeled as THC-free (sometimes called “broad spectrum” or “CBD isolate”) rather than full-spectrum hemp extracts, which retain small amounts of THC by design.
Drug Interactions to Watch For
CBD inhibits a family of liver enzymes responsible for breaking down many common medications. When these enzymes are blocked, drugs that your cat takes can build up to higher-than-expected levels in the bloodstream, essentially making the same dose stronger. This is particularly relevant for cats on seizure medications like phenobarbital. Research has shown that CBD can slow phenobarbital metabolism enough to raise blood concentrations at the same administered dose, increasing the risk of side effects from that drug.
The same enzyme pathway processes many other medications, so if your cat takes any prescription drugs, the potential for interaction is real. This is one area where a conversation with your veterinarian is genuinely important, not just a formality.
No FDA-Approved CBD Products for Animals Exist
As of early 2025, no CBD product has received FDA approval, conditional approval, or indexing for use in animals. The FDA considers any CBD product marketed to treat or prevent disease in animals to be an unapproved animal drug. The agency has acknowledged that research is ongoing but has noted “significant data gaps” around many aspects of CBD use in animals.
This regulatory gap means the products available to you are essentially supplements operating in a gray area. Nobody is verifying that a given product contains what it says on the label, unless the manufacturer voluntarily submits to third-party oversight.
How to Choose a Safer Product
The most reliable marker of quality is the NASC (National Animal Supplement Council) Quality Seal. Companies displaying this seal must pass biannual audits by an independent third party, maintain detailed quality control procedures, submit to random product testing by an independent lab, and comply with specific labeling guidelines. They also need a complaint tracking system and must participate in annual training. It’s not a guarantee of perfection, but it filters out the worst offenders in a largely unregulated market.
Beyond the seal, look for products that provide a certificate of analysis (COA) from a third-party lab. This document should confirm the CBD content matches the label and verify that THC levels are either undetectable or well below 0.3%. It should also screen for contaminants like pesticides, heavy metals, and residual solvents. If a company can’t or won’t provide a COA, move on.
Practical Dosing Considerations
The clinical trials that demonstrated safety in cats used 4 mg/kg body weight per day, given with food. For a 10-pound (4.5 kg) cat, that works out to roughly 18 mg of CBD daily. Most veterinarians who recommend CBD suggest starting well below this level, often around 1 to 2 mg/kg, and increasing gradually while watching for side effects like excessive sedation or gastrointestinal upset.
Giving CBD with food improves absorption. Oil-based tinctures tend to offer more precise dosing than treats, since you can measure exact amounts. Avoid products formulated for humans, which may contain ingredients like xylitol or essential oils that are toxic to cats, and which make accurate small-dose measurement difficult.
If your cat becomes unusually sleepy, wobbly, or stops eating after starting CBD, reduce the dose or stop entirely. These signs could reflect a dose that’s too high, a sensitivity to one of the carrier ingredients, or a product that contains more THC than advertised.