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Peppermint
Mentha × piperita
Peppermint (Mentha x piperita) is mildly toxic to cats. The plant is rich in menthol and pulegone — monoterpenoid compounds that cats cannot efficiently metabolise due to limited hepatic glucuronidase activity. While fresh plant nibbling usually causes only mild GI upset, peppermint essential oil is significantly more concentrated and far more dangerous.
Important Notes
Toxic compounds: menthol, pulegone, and related monoterpenoids; essential oil is 50-100x more concentrated than fresh leaves
Mechanism: impaired feline hepatic metabolism of terpenoids leads to GI irritation and liver stress; high doses cause CNS depression
Symptoms: vomiting, diarrhea, drooling, lethargy; peppermint oil can cause tremors, weakness, and liver damage
Never apply peppermint oil to a cat's skin or fur — topical exposure causes rapid systemic absorption
Diffusing peppermint oil in closed spaces is also harmful; use in well-ventilated areas away from cats
Potentially Toxic Parts
Leaf
Possible Symptoms Reported in Cats
Vomiting, diarrhea, nausea, excessive drooling (hypersalivation), difficulty swallowing, and loss of appetite
Gastrointestinal · Not explicitly specified in the provided sources.
Lethargy, weakness, uncoordinated gait (walking as if drunk/ataxia), muscle tremors, and seizures
Gastrointestinal · Not explicitly specified in the provided sources.
Difficulty breathing, breathing with the mouth open, coughing, and sneezing
Respiratory · Not explicitly specified in the provided sources.
Liver damage progressing to liver failure
Hepatic · Not explicitly specified in the provided sources.
Skin irritation, redness, or chemical burns on the skin, lips, gums, and tongue
Dermal · Not explicitly specified in the provided sources.
Disclaimer: This summary was compiled from multiple sources and is for informational use only. It is not a diagnosis or treatment plan. Toxicity can vary based on the substance, amount, plant part, and individual cat. If you think your cat may have been exposed to a toxic substance, contact a veterinarian right away.