With caution — cats and tomatoes
Ripe red tomatoes are low risk for cats in very small amounts. Green tomatoes, tomato plant leaves, and stems contain solanine and tomatine at concentrations that cause toxicity. The processed tomato products most cats encounter (sauces, paste, ketchup) are additionally dangerous because they contain garlic and onion. The garden tomato plant is the most common real hazard.
🏆 PawKeen Safety Score™ — Tomatoes for Cats
“I see tomato-related enquiries mostly in summer when people are growing tomatoes in Australian backyards. The cats that access the garden are much more likely to chew on the abundant leafy plant than on the ripe fruit hanging above them. The solanine and tomatine content of the leaves is high enough to cause GI and CNS symptoms. If a cat has been in a tomato patch, assess which parts they accessed — not just whether they found a red tomato.”
The straight answer
Ripe red tomatoes are low risk for cats at small amounts. The tomato plant — leaves, stems, and green fruit — contains solanine and tomatine at concentrations that can cause toxicity in cats. Most of the real-world risk comes from cats accessing tomato plants in Australian vegetable gardens, not from deliberate feeding of ripe fruit. The processed tomato products (sauces, pastes) that show up in home cooking almost always contain garlic and onion, which are the more urgent concern.
Ripe vs. unripe — the chemical reason they’re different
As a tomato ripens, the plant converts most of its tomatine content — a glycoalkaloid defence compound — into tomatidine and other less bioactive metabolites. A ripe red tomato contains approximately 5–9mg of tomatine per kilogram; an unripe green tomato can contain several hundred mg/kg. The leaves and stems maintain high concentrations regardless of fruit ripeness.
This transformation is why ripe tomato flesh sits in a different risk category from the plant or the green fruit. A cat licking a ripe tomato slice receives a very low tomatine dose. A cat chewing on tomato leaves gets a much higher dose.
Australian vegetable garden context
Home-grown tomatoes are extremely common across Australian states — Queensland and Victoria in particular have long growing seasons and high rates of home vegetable gardening. In summer, a cat with outdoor access to a vegetable patch will encounter tomato plants routinely.
The practical guidance: stake or cage tomato plants to keep the lower foliage off the ground and less accessible to cats. Consider physical barriers around the tomato bed during the growing season if you have cats that actively explore the garden. The ripe tomatoes at harvest height are less concerning than the sprawling leafy growth below.
Note: For an identical question answered with the same information, see our can cats eat tomato article.
What makes tomato products more dangerous than fresh tomatoes
The majority of tomato-related calls to veterinary helplines in Australia involve cats that ate food containing tomato-based sauces — pasta sauce, pizza base, tomato paste — rather than fresh tomatoes. These products consistently contain garlic and onion as core flavouring ingredients, both of which cause haemolytic anaemia in cats.
If your cat ate any amount of a commercial tomato product, the relevant question is not about the tomato — it is about the garlic and onion content of the sauce. Call the Animal Poisons Helpline on 1300 869 738 and describe the product.
Symptoms of solanine toxicity in cats
From the green plant parts: GI upset (vomiting, diarrhoea, hypersalivation), lethargy, dilated pupils, and in higher doses, bradycardia (slowed heart rate) and CNS depression. Onset is usually within 1–4 hours of ingestion. Most cats that access garden leaves will show only mild GI symptoms and recover without treatment; significant exposures (a cat that ate substantial leaf material) warrant veterinary assessment.
🚨 My Cat Ate Tomatoes — What Now?
If your cat ate tomato plant leaves, stems, or green/unripe tomatoes, call the Animal Poisons Helpline on 1300 869 738. Ripe tomato flesh alone — monitor for mild GI symptoms.
Signs that warrant a vet call:
- Lethargy
- GI upset
- drooling
- dilated pupils
- slow heart rate after exposure to tomato plant leaves or green tomatoes. Mild GI upset from ripe flesh only
If your cat ate a large amount or is showing the signs above: Don’t wait — call immediately.
📞 Animal Poisons Helpline: 1300 869 738
Available 24/7 across Australia. Have your cat’s weight, breed and approximate quantity consumed ready when you call.
Frequently Asked Questions
Most cats do not find ripe tomatoes attractive — the acidity and the plant compounds are not palatable to obligate carnivores. This is actually ideal. Cats that show no interest in tomatoes present no garden access risk.
For more on vegetable safety for cats, see our guides to green beans and our cat food safety hub.
📚 Sources & Further Reading
- ASPCA Animal Poison Control — Tomato Plant. https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants
- Friedman M. Tomato glycoalkaloids: role in the plant and in the diet. J Agric Food Chem 2002.
- Cornell Feline Health Center — Plant Safety for Cats. https://www.vet.cornell.edu
- Australian Veterinary Association — Backyard Garden Safety for Cats. https://www.ava.com.au
