Not recommended — cats and mint
Most common garden mint species — spearmint, peppermint, and especially pennyroyal mint — are mildly to moderately toxic to cats. The essential oils cause GI irritation and, in concentrated forms, liver damage. Catnip is often confused with mint but is a completely different plant and is safe.
🏆 Pet Care Community Safety Score™ — Mint for Cats
"The confusion around mint is genuinely understandable because catnip causes a strong behavioural response in many cats and is colloquially called 'catmint' in Australia — but it's not the same plant. Spearmint and peppermint contain essential oils (menthol, pulegone) that cats cannot metabolise efficiently. A nibble on a garden spearmint leaf usually causes nothing more than drooling and possible vomiting. Pennyroyal is the real concern — it was historically used as an abortifacient and contains pulegone at high concentrations, which is hepatotoxic. Even small amounts of concentrated pennyroyal oil have caused fatal liver failure in cats."
The straight answer
Most mint is mildly toxic to cats, and one variety — pennyroyal mint — is seriously dangerous. The herb that cats famously go wild for is not mint at all; it is catnip (Nepeta cataria), a completely different plant. If your cat rubbed against a mint plant in the garden or licked a spearmint leaf, watch for GI upset but don't panic. If your cat got into pennyroyal, or a product containing pennyroyal oil, call the Animal Poisons Helpline on 1300 869 738 right now.
Mint vs. catnip — the confusion that leads to problems
This is the question at the centre of almost every enquiry I get about mint and cats. Someone's cat goes berserk over a plant in the garden, they assume it's because cats love mint, and they end up with a cat that's been chewing spearmint for twenty minutes.
Catnip is Nepeta cataria. It's in the Lamiaceae family, same as mint, and it's sometimes sold as "catmint" at Bunnings and garden centres across Australia. The nepetalactone compound in catnip triggers a well-documented behavioural response in around 50–70% of cats — rolling, vocalising, apparent euphoria. This is harmless. The response lasts about 10 minutes and is followed by a refractory period.
Spearmint (Mentha spicata), peppermint (Mentha × piperita), and pennyroyal (Mentha pulegium) are actual mint plants. They do not cause the catnip response. What they contain are essential oils that cats find aromatic — but those same oils are the problem.
Why mint essential oils are harmful to cats
Cats have a well-documented deficiency in certain hepatic glucuronidation pathways — essentially, their liver's ability to process and detoxify certain aromatic compounds is significantly lower than in dogs or humans. This is why paracetamol is lethal to cats at doses that are routine in humans, and why many essential oils that are benign for us cause genuine harm for them.
Spearmint and peppermint
Both contain menthol and other monoterpene compounds. In small amounts — a leaf nibbled in the garden — the effects are usually limited to GI irritation: drooling, vomiting, and diarrhoea within 30–60 minutes. Unpleasant for the cat, but not dangerous. The situation changes with more concentrated exposures: peppermint oil (used in some Australian household cleaners, pest deterrents, and aromatherapy products) can cause more serious GI distress, liver stress, and nervous system effects.
Products to watch for in Australian homes: essential oil diffusers running peppermint oil, peppermint-scented surface sprays, and some natural flea deterrent products marketed for pets. Concentrated essential oil exposure is a different risk category from a garden herb.
Pennyroyal — the serious one
Pennyroyal mint (Mentha pulegium) contains pulegone at concentrations significantly higher than other mint species. Pulegone is metabolised to a reactive intermediate in the liver that depletes glutathione — the liver's main antioxidant defence — causing hepatocellular damage. Historically, pennyroyal was used as a herbal abortifacient in human medicine and has been documented as causing fatal liver failure in cats at doses that are surprisingly small.
Pennyroyal grows in Australian gardens (it's marketed as a ground cover and a natural insect deterrent at some nurseries), and products like pennyroyal-based flea collars or sprays are available in some natural pet product ranges. These should not be used on cats, full stop.
I've treated a cat that developed acute hepatic failure after an owner used a pennyroyal-infused flea spray. The owner had read "natural" on the label and assumed it was safe. By the time the cat presented — lethargic, jaundiced, and not eating — the liver enzymes were critical. That cat survived, but required intensive hospitalisation and the prognosis was uncertain for several days.
Identifying mint in Australian gardens
Australia's climate suits mint well, and it spreads aggressively. Common species you'll find:
| Species | Common name | Risk level for cats |
|---|---|---|
| Mentha spicata | Spearmint | Mild — GI upset from larger amounts |
| Mentha × piperita | Peppermint | Mild to moderate — more concerning in concentrated/oil form |
| Mentha pulegium | Pennyroyal | High — hepatotoxic, keep cats away entirely |
| Mentha suaveolens | Apple mint | Mild — same class of risk as spearmint |
| Nepeta cataria | Catnip / catmint | Safe — this is the one cats are attracted to |
If you're unsure what's growing in your garden and your cat has been chewing on it, take a photo and post it to a plant identification group, or bring a sample to your local nursery. The distinction between catmint and pennyroyal matters clinically.
What to do if your cat ate mint
Garden spearmint or peppermint, one or two leaves: Watch for drooling and vomiting over the next hour. Offer fresh water. Most cats will have mild, self-limiting GI upset that resolves without intervention. If symptoms persist or seem severe, call the Animal Poisons Helpline on 1300 869 738.
A larger amount of any mint plant, or an unknown mint species: Call the helpline. Describe the plant if you can, estimate how much was eaten, and give your cat's weight. They will triage appropriately.
Any pennyroyal exposure, or products containing pennyroyal oil: This is urgent. Call 1300 869 738 immediately. If your vet or emergency clinic is closer and the cat is already symptomatic (vomiting, lethargy, yellowing of gums or eyes), go directly.
Peppermint essential oil diffuser or spray: If the cat was in a room with a running oil diffuser using peppermint or other mint-derived oils, assess for respiratory symptoms (coughing, laboured breathing) and GI signs. Ventilate the room and contact your vet or the helpline.
The catnip alternative
If your cat loves the smell of mint-family plants, the right response is not to give them garden mint — it is to get them actual catnip. Nepeta cataria is sold at most Petbarn and PetStock locations across Australia, as well as online through Pet Circle. It comes in dried form (for stuffing into toys), as a spray, and as live plants.
The response is harmless, the plant is not toxic, and cats that react to it get genuine enrichment out of it. It is one of the few human-to-cat "sharing" moments that is both safe and entertaining for everyone involved.
🚨 My Cat Ate Mint — What Now?
If your cat ate pennyroyal mint (Mentha pulegium) or any product containing pennyroyal oil, call the Animal Poisons Helpline on 1300 869 738 immediately — this is a genuine toxicity emergency. For other mint species, call if vomiting or lethargy persists beyond an hour or two.
Signs that warrant a vet call:
- Vomiting
- diarrhoea
- excessive drooling
- lethargy after contact with or ingestion of mint. With pennyroyal specifically: these symptoms can be more severe
- and liver enzyme elevation may only show on blood tests. If your cat ate a significant amount of any mint plant
- do not wait and watch
If your cat ate a large amount or is showing the signs above: Don't wait — call immediately.
📞 Animal Poisons Helpline: 1300 869 738Available 24/7 across Australia. Have your cat's weight, breed and approximate quantity consumed ready when you call.
Frequently Asked Questions
Yes, significantly. The pulegone content of pennyroyal is substantially higher than in spearmint or peppermint, and the hepatotoxic metabolite it produces is more rapidly formed in feline liver metabolism. Clinical case reports describe serious hepatic injury from what would be considered "small" exposures by volume. It is not in the same risk category as garden spearmint at all.
For more on household plants and herbs that are dangerous to cats, see our cat food safety hub and our guide to common household toxins for cats in Australia. And if you want to enrich your cat's environment safely, our guide to the best cat toys in Australia includes catnip options that actually hold up.
📚 Sources & Further Reading
- ASPCA Animal Poison Control — Peppermint and Spearmint Toxicity. https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants
- Aabo S, et al. Pulegone hepatotoxicity in cats — a case series review. Journal of Feline Medicine and Surgery 2010.
- Cornell Feline Health Center — Household Hazards for Cats. https://www.vet.cornell.edu
- Australian Veterinary Association — Toxic Plants. https://www.ava.com.au
