Can smoking marijuana around my cat cause her harm?

Marijuana is also known as cannabis, weed, pot, dope or grass. The best way to answer the question in the title is to ask whether marijuana can harm people and then look for any studies which indicate that it can harm animals as well. But first…

Marijuana is stronger today

I’m sure you’ve read that marijuana being sold today in the United States and other countries is 3 to 10 times more potent than the marijuana sold in the past, even the very recent past (New York Times and other sources). Although, apparently, information about cannabis from 1960s and 70s is unreliable. But there’s been a clear rise in THC from around 4% in 1995 to around 16% in 2018. Higher THC strains are more likely to cause a psychotic illness in people at risk of that illness.

Is smoking marijuana around your cat harmful to your cat?
Is smoking marijuana around your cat harmful to your cat? Photo by Harrison Haines from Pexels
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Is marijuana harmful to people?

Ten percent of people become addicted to it. Drug addiction is a terrible disease which greatly damages one’s life. The NHS in England says that regular cannabis use increases your risk of developing a psychotic illness such as schizophrenia. Cannabis can be harmful to the lungs if smoked regularly and it can cause bronchitis. It also contains cancer-causing chemicals. Regular long-term use can cause cardiovascular disease and a stroke.

Is marijuana harmful to cats?

On a commonsense basis, bearing in mind the above, marijuana is potentially harmful to cats depending upon how much of it is ingested which in turn depends upon how often it is used and for how long by the cat’s owner and/or other people living with the cat concerned.

A study published on Science Direct dated 1991, states that damage to the brain or peripheral nervous system of animals depends upon the duration that the animal is exposed to THC. They found that if they exposed a rodent to THC for 8-10% of its life it had a neurotoxic effect in rats around the time of puberty. This would equate to about 7 to 10 years of exposure in humans (about one eighth of a lifespan). One eighth of a cat’s lifespan is about 2 years. So two years of regular exposure to a young cat might harm the cat’s brain. The increased strength of marijuana has probably elevated this risk.


The question in the title is quite widely phrased. The answer has to be a distinct Yes. Marijuana can harm a cat but it depends upon the degree of usage of the drug, whether the cat is around the user a lot, the age of the cat and so on.

It goes without saying really that a good cat owner does not knowingly expose their companion animal to harm, even potential harm. The duty is to do the opposite: to keep their cats safe. I don’t think a regular user of marijuana should be a cat owner. They’re just not suited to the job. If you are one of those people then please consider rehoming your cat.

Note: Study referred to: Neurotoxicology of cannabis and THC: A review of chronic exposure studies in animals.

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