Orange

What orange trees do to a cat.

Yes — orange trees are toxic to cats. The ASPCA lists Citrus sinensis as Toxic to Dogs, Toxic to Cats, Toxic to Horses. The toxic principles are essential oils and psoralens. Clinical signs are vomiting, diarrhea, depression, and potential dermatitis. The fruit is edible, but skins and plant material can cause problems.

Orange (Citrus sinensis, family Rutaceae) shares the same toxicity profile as all citrus trees — lemon, lime, and grapefruit are all ASPCA-listed toxic to cats with the same toxic principles.

The ASPCA data, verbatim

The ASPCA listing for orange states:

Scientific Name: Citrus sinensis · Family: Rutaceae · Toxicity: Toxic to Dogs, Toxic to Cats, Toxic to Horses · Toxic Principles: Essential oils and psoralens · Clinical Signs: Vomiting, diarrhea, depression; potential dermatitis. Fruit is edible, skins and plant material can cause problems.

Essential oils: limonene and linalool

The essential oils in orange include limonene (the compound that gives oranges their scent) and linalool (a terpene alcohol found in many citrus plants). Both are toxic to cats because cats lack the liver enzymes needed to metabolise terpenes efficiently. The compounds accumulate and cause the vomiting, diarrhea, and depression the ASPCA lists.

Psoralens: the phototoxic dermatitis risk

Psoralens are compounds that become toxic when exposed to ultraviolet light. A cat that gets orange peel oil on its fur — from rubbing against the tree, playing with a fallen orange, or licking a surface where orange juice has dried — can develop phototoxic dermatitis on any skin exposed to sunlight. The psoralens activate under UV, causing inflammation and skin damage.

Fruit flesh vs skins and plant material

The ASPCA makes an important distinction: the fruit is edible, but skins and plant material can cause problems. The toxicity is concentrated in the peel oil and plant tissue, not the juicy fruit flesh. The safe approach is to keep all orange plant material — peels, leaves, stems, and fallen fruit — away from cats.

What to do if your cat eats orange plant material

1. Call your vet or ASPCA Animal Poison Control at (888) 426-4435.
2. Remove any remaining plant material from your cat's mouth.
3. Tell the vet exactly what part was eaten — peel, leaf, or flesh — and how much.

Safe garden alternatives

If you want a cat-safe fruiting or flowering plant, strawberry, sunflower, and calendula are all ASPCA-listed non-toxic to cats.

The bottom line

Orange (Citrus sinensis) is toxic to cats per the ASPCA. The essential oils and psoralens cause vomiting, diarrhea, depression, and potential dermatitis. The same toxicity applies to all citrus — lemon, lime, and grapefruit. The fruit flesh is edible, but the skins, leaves, and stems are the problem.