The short answer: It is not recommended.
The long answer: Red, plump, and naturally sweet, tomatoes are packed with nutrients such as vitamin C, vitamin K, potassium, folate, and lycopene. However, this fruit is not recommended for cats because it contains solanine and alpha-tomatine that are mildly toxic to cats. These chemical compounds are found in the tomato plant and its unripe fruits.
If you own a tomato plant, keep it away from your cat at all times. If she nibbles on the plant’s stems or leaves, she may exhibit any of the following symptoms: excessive salivation, lack of appetite, diarrhea, extreme stomach upset and vomiting, drowsiness, confusion, behavioural changes, central nervous system depression, apathy, physical weakness, slowed heart rate, and dilated pupils.
Although ripe tomatoes are not lethal for cats, feeding your cat tomato sauce or tomato soup is also not recommended. This is because of the additional ingredients used to make them such as salt, sugar, garlic, and onion. These flavourings are known to be harmful for cats.
What to do if your cat accidentally eats the tomato plant or its unripe fruit: Contact your veterinarian immediately while keeping a close eye on your cat. Also, try to find out how much of it she has consumed. If your pet cat ate a part of the plant, take a sample with you to show the vet.
In summary: From the plant to its unripe fruits, tomatoes should not be eaten by your pet cat. Eating them may result in poisoning and other uncomfortable side effects. Instead of tomatoes, discover which human food cats can safely consume in our “can cats eat” category.