There is no over-the-counter “Plan B” pill for cats, but veterinarians do have prescription options that can prevent or terminate an unwanted feline pregnancy. None of these medications are FDA-approved for use in cats in the United States, and all require veterinary supervision. If your cat has mated unexpectedly, acting quickly and contacting your vet is the most important step.
What Options Exist
Veterinarians can use several types of injectable or oral medications to end a feline pregnancy at different stages. The most common approaches work by either blocking the hormone progesterone (which a cat needs to maintain pregnancy) or by causing the uterus to contract and expel embryos or fetuses.
Aglepristone is a progesterone-blocking drug given as two injections 24 hours apart. When given early (within roughly 24 days of ovulation), it causes embryos to die before they implant in the uterine wall. Between days 25 and 35, embryos are reabsorbed by the body. After day 35, the cat will expel the fetuses, which is a more involved process requiring monitoring.
Synthetic prostaglandins are another option. These drugs cause uterine contractions. A drug called cloprostenol is generally preferred over older prostaglandins because it targets the uterus more precisely and causes fewer side effects like vomiting or diarrhea. Some vets use a combination protocol pairing a prostaglandin with a drug that suppresses the hormone prolactin. This combination approach has the highest reported success rates with the shortest treatment times, though the medications often need to be custom-made by a compounding pharmacy.
Why There’s No Over-the-Counter Option
No feline emergency contraceptive is FDA-approved in the United States. The medications veterinarians use are either approved for other species, approved in other countries, or compounded specifically for the situation. Cornell University’s veterinary college notes that cat-specific doses are typically only available through compounding pharmacies, and handling these drugs requires care because some can be absorbed through human skin.
This means you cannot walk into a pet store or order something online to prevent your cat’s pregnancy. Every option requires a veterinary exam and prescription.
Never Give Your Cat Human Medications
Human birth control pills are toxic to cats, even in tiny amounts. The hormones and inactive ingredients in human contraceptives are formulated for a body roughly 15 to 30 times larger than a cat’s, with entirely different metabolism. Giving your cat any human medication without veterinary guidance can cause organ damage or death.
Your Vet May Recommend Waiting First
Not every mating results in pregnancy. In dogs, roughly 60 percent of accidental matings don’t lead to conception, and cats can have similar variability. Your vet may suggest confirming pregnancy with an ultrasound before starting any drug protocol, particularly because these medications carry their own risks. If your cat isn’t actually pregnant, there’s no reason to expose her to side effects.
The exception is if you’ve already decided to have your cat spayed. In that case, spaying can be performed whether or not she’s pregnant, and it permanently solves the problem. Many vets consider spaying the safest and most straightforward option after an accidental mating, especially if you weren’t planning to breed your cat.
What to Expect During Treatment
If your vet does prescribe a pregnancy termination protocol, the process typically involves one or more visits for injections, followed by ultrasound monitoring to confirm the treatment worked. Prostaglandin-based treatments may require injections every 12 to 24 hours over several days, with ultrasound used to verify that the uterus has fully emptied. Aglepristone treatment is simpler in terms of dosing (two injections, one day apart) but still requires follow-up imaging.
Side effects vary by drug. Prostaglandins can cause temporary vomiting, restlessness, panting, and diarrhea, though the newer synthetic versions produce milder reactions. Aglepristone is generally well tolerated. Your vet will monitor your cat closely during and after treatment.
Timing Matters
The earlier you act after an accidental mating, the more options your vet has and the simpler the process tends to be. Early treatment (within the first few weeks) typically results in embryos being reabsorbed quietly by the body, with no visible signs of pregnancy loss. Later treatment, past about five weeks, involves actual expulsion of fetuses, which is harder on the cat physically and emotionally harder for owners to witness.
If you know or suspect your cat has mated, call your vet within the first day or two. Even if they recommend waiting to confirm pregnancy before treating, having that conversation early gives you the full range of options.