Is St. John's wort poisonous to dogs and cats?

Updated 2026-09-30 · 1 sources

Based on: NC State Extension Gardener Plant Toolbox

Call a vet today

St. John's wort is poisonous to dogs and cats – call your vet today for advice if your pet has eaten any of it. The leaves and sap/juice are listed as poisonous.

Dogs Call a vet today
Cats Call a vet today

What to do now

What to do right now

Call your vet or the nearest emergency vet.
Note which plant, which part, how much and when.
Take a photo or a piece of the plant with you.
Remove what is left and move the plant out of reach.
Keep your pet calm.

Don't

Do not make your pet vomit unless a vet tells you to.
Do not give your pet any human medicine.

Why it can be dangerous

St. John's wort is listed as a problem for cats and dogs.^[1]

Signs to watch for

Skin becoming sensitive to sunlight
Gastrointestinal upset
Allergic reactions
Fatigue
Ulcerative and exudative dermatitis

Scientific name: Hypericum
Poisonous parts: leaves, sap/juice

What the experts say

“Problems: Problem for Cats, Problem for Dogs, Problem for Horses”
— NC State Extension Gardener Plant Toolbox [1]

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

OkPaw is on Android now – an iPhone version is on its way.

Common questions

Is St. John's wort a problem for cats?

Yes. It is listed as a problem for cats.^[1]

Is St. John's wort a problem for dogs?

Yes. It is listed as a problem for dogs.^[1]

Sources

NC State Extension Gardener Plant Toolbox

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages