Can Contraceptive Pills Affect Your Cat's Health?

In today's article, we'll answer the question of whether or not contraceptive pills affect your cat's health and why. Watch out for its side effects!
Can Contraceptive Pills Affect Your Cat's Health?

Last update: 24 March, 2019

Although getting your cat spayed is the best way to avoid her getting pregnant, some owners choose different options that aren’t as drastic. One example are contraceptive pills. In today’s article, we’ll tell you if they’ll affect your cat’s health.

Contraceptive pills for cats: what to know

A lot of owners want to prevent their pets from having babies, but they don’t want to castrate or sterilize them. Or, in other cases, the animal may have a health problem—like a heart problem—that means they can’t have surgery, no matter how simple it may be.

Another case may be a female that’s recovering from an operation or a disease that won’t allow her to get spayed.

In these cases, the vet will recommend an alternative treatment: contraceptive pills, similar to those that are taken by women. These drugs are taken orally and their goal is to keep cats and dogs from getting pregnant. The pills will keep the animals from going through heat and ovulation because they contain a large amount of progestin. 

In order for the pills to be effective, it’s very important that you follow the instructions exactly. That means, you can’t forget to give your cat any of her doses, and you have to follow your veterinarian’s directions.

The best way to do this is to hide the pill in her food. It’s best to use soft food (cheese, pâté, tuna, wet food). This will ensure that your cat consumes everything.

An owner giving her cat contraceptive pills.

Contraceptive injections are another option to avoid getting pregnant. The vet will give your pet these shots every few months, according to the appropriate guidelines. The disadvantage of this treatment is that we have to take the cat to the clinic every few months.

Will contraceptive pills put my cat’s health at risk?

As you can guess, a treatment based on synthetic hormones can’t be completely safe for our pet, especially if you do it for a long period of time.

Birth control pills should only be used as a last resort. That means, only if your cat can’t be spayed , because these pills can have harmful side effects on our cat’s health.

One of the main consequences is that it significantly increases the possibility of developing malignant tumors, breast cancer or uterine cancer. This is because of the hormonal imbalance in the reproductive system. 

Additionally, these pills increase the likelihood of getting different infections, mainly in the uterus. These infections are known as pyometra, and they’re at the urinary level.

A grey cat looking suspicious.

The cat’s health isn’t the only thing that will be affected. Their behavior will also change, and they’ll become more predisposed to a sedentary lifestyle. They won’t want to play or be as active as before, and they’ll experience greater anxiety about food (and may become overweight as a consequence). Additionally, there are some cases of cats that lose their hair even when it’s not shedding season.

Other risks

You should also know that this method of birth control isn’t 100% effective. It can also cause irregular cycles that can also end in pregnancy. In the riskiest cases, the pregnancy may endanger the life of the cat and her babies.

Some kittens may be born with malformations and die within a few hours. As for the mother, having babies die in the womb may be fatal. This is because it will be difficult to give birth to them.

Contraceptive pills can have many harmful effects on cats’ health, so they should only be used as a last resort, when castration isn’t an option. In addition, experts don’t recommend carrying this treatment out for a long time. And it should always be accompanied by periodic visits to the vet so she can analyze the animal’s condition.


All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.


  • Rivera, M. (2015). Control del ciclo reproductivo en la perra y en la gata | Argos Portal Veterinaria.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.