Toxic Herbs & Plants for Pets
Many herbs safe for humans are dangerous or lethal to pets. This reference covers the most common toxic herbs, with special attention to species-specific dangers.
If your pet has ingested a toxic substance, contact your veterinarian or the ASPCA Animal Poison Control Center: (888) 426-4435
Herbs Toxic to Pets
| Herb / Plant | Toxic To | Danger | Severity |
|---|---|---|---|
| Tea Tree Oil (Melaleuca) | Dogs, Cats (especially) | Neurotoxic — even topical application can cause tremors, ataxia, and coma | high |
| Pennyroyal | Dogs, Cats | Hepatotoxic — historically used as flea repellent but can be deadly | high |
| Comfrey (internal) | Dogs, Cats | Pyrrolizidine alkaloids cause liver damage — topical use only | moderate |
| Ephedra / Ma Huang | All species | Cardiovascular stimulant — can cause seizures and death | high |
| Wormwood / Artemisia | Dogs, Cats | Thujone is neurotoxic — seizure risk | high |
| Garlic | Cats (especially), Dogs (dose-dependent) | Causes Heinz body anemia — cats are far more sensitive | moderate |
| Onion (Allium cepa) | All pets | Hemolytic anemia in all species | high |
| Lily (various) | Cats (extremely) | Acute kidney failure from even small exposure | high |
| Aloe Vera (latex/rind) | Dogs, Cats | Saponins cause GI distress — inner gel may be okay topically | moderate |
| Black Walnut | Dogs | Used in some dewormers but toxic at wrong doses | moderate |
| Eucalyptus | Cats, Dogs | Essential oil form is particularly dangerous | high |
| Oregano Oil | Cats | Phenols are hepatotoxic to cats | high |
| Wintergreen | All pets | Methyl salicylate — causes aspirin-like toxicity | high |
| Yucca (excess) | Dogs | Saponins cause GI irritation in excess — small amounts used medicinally | low |
This is not an exhaustive list. Many more plants and herbs can be harmful to pets. When in doubt, consult your veterinarian before giving any herb to your pet.
Essential Oils & Pets
Essential oils are one of the most common sources of pet poisoning. Cats are especially vulnerable because they lack the liver enzymes needed to metabolize many volatile compounds.
- Cats lack the liver enzymes (glucuronidation) to metabolize most essential oils
- Never apply undiluted essential oils to any animal
- Diffusing essential oils around cats can cause respiratory distress
- Tea tree, eucalyptus, oregano, wintergreen, and pennyroyal oils are especially dangerous
- Even "pet-safe" essential oil blends should be used with extreme caution
- Consult a veterinarian trained in aromatherapy before any essential oil use on pets
Why Cats Are Special
Cats have a deficiency in hepatic glucuronidation (they lack the UGT1A6 enzyme). This means they cannot metabolize phenols, phenolic compounds, salicylates, most essential oils, and many terpenes and terpenoids. Compounds that dogs and humans handle easily can accumulate to toxic levels in cats.
The safe herb list for cats is much shorter than for dogs. Never assume that because an herb is safe for dogs, it is also safe for cats. Always verify the species-specific safety rating before giving any herb to a cat.
Check Individual Herb Safety
Every herb in our library has species-specific safety ratings. Look up any herb before giving it to your pet.