Wormwood (Artemisia absinthium) is classified as toxic to dogs, cats, and horses by the ASPCA Animal Poison Control Center[1]. There is no published dosing study establishing a safe amount for dogs or cats. Do not give wormwood, wormwood essential oil, or wormwood tinctures to a pet without direct veterinary guidance.
- Livestock studies of wormwood extracts against gastrointestinal nematodes in sheep and goats found activity in laboratory tests, and a 2009 sheep study reported reduced egg output, but a 2020 sheep study and a 2025 goat study found no significant effect on egg counts in the treated animals[2][3][4]
- These studies used controlled agricultural dosing (crude extracts measured in mg/mL or mg/kg) under veterinary parasitology protocols — not a consumer product label
- No equivalent controlled study exists for dogs or cats at any dose
- The ASPCA lists Artemisia species, including wormwood, as toxic to dogs, cats, and horses, with large ingestions linked to vomiting, seizures, and liver damage[1]
Wormwood has a long history as a traditional deworming agent in livestock, and a growing body of veterinary parasitology research has tested that traditional use, with mixed results — in sheep and goats specifically. That research does not extend to dogs or cats, and the same plant is formally listed as a toxic hazard for companion animals. This article separates what the livestock research actually shows from what it does not support.
What the Livestock Research Actually Shows
Three peer-reviewed veterinary parasitology studies have tested wormwood extracts against gastrointestinal nematodes in small ruminants (sheep and goats), the animals it has been studied in most:
- Sheep, 2020: Lambs experimentally infected with Haemonchus contortus (barber’s pole worm) were supplemented with dried wormwood. Aqueous extracts showed a strong ovicidal (egg-killing) effect in vitro, with an ED50 of 1.40 mg/mL, but the mean eggs per gram of treated and untreated lambs did not differ[2].
- Sheep, 2009: Crude ethanolic extracts of wormwood were compared directly against albendazole, a standard veterinary anthelmintic drug, in sheep with GI nematode infections. The extract significantly reduced faecal egg output and was reported as comparably effective to the reference drug in this trial[3].
- Goats, 2025: Free-grazing Creole goats in Peru with natural nematode infections were treated orally with 600 mg/kg of wormwood ethanolic extract. In vitro larval motility inhibition reached 81.79% at the highest tested concentration, but the in vivo fecal egg count reduction test showed no significant effect[4].
These are legitimate, controlled studies with measurable outcomes (egg counts, larval motility, in vitro dose-response curves) — not anecdotal reports. That’s meaningfully different from most herbal pet-deworming claims, which usually cite no controlled animal data at all.
Why This Doesn’t Translate to Dog or Cat Dosing
Three things separate this research from “wormwood is safe to deworm your dog”:
- Species matters. Sheep and goats are ruminants with a fundamentally different digestive system (a multi-chambered stomach with a rumen microbiome that processes plant compounds very differently from a dog or cat’s single-chambered gut). A dose and metabolic outcome studied in a ruminant cannot be assumed to carry over to a monogastric carnivore.
- The dosing in these studies is not a home-use protocol. The 2025 goat study used 600 mg/kg of a specifically prepared ethanolic extract under research conditions with monitored animals — not a capsule, tincture, or tea bought off a shelf.
- No dog- or cat-specific trial exists. A PubMed search for controlled wormwood dosing or toxicity studies in dogs returns no results. The absence of a study is not evidence of safety — it means the question hasn’t been formally tested in that species.
Is Wormwood Toxic to Dogs and Cats?
Yes, according to the ASPCA Animal Poison Control Center, which lists Artemisia species (including wormwood) as toxic to dogs, cats, and horses. Reported effects from large ingestions include vomiting, seizures, and liver damage[1]. The Merck Veterinary Manual similarly catalogs herbal and dietary supplements, including thujone-containing plants like wormwood, among substances that can cause toxicosis in companion animals when ingested outside a controlled, veterinarian-directed context[5].
Thujone, the same compound responsible for wormwood’s regulatory history in human absinthe production, is a neurotoxic compound at sufficient doses in any mammal, and dogs and cats are smaller-bodied than the livestock species studied, which narrows any real margin of safety even further.
Traditional Veterinary Use vs. Modern Evidence
Wormwood’s use as a livestock dewormer predates modern veterinary pharmacology by centuries, and interest in it has resurfaced specifically because of rising anthelmintic drug resistance in parasites like Haemonchus contortus — the studies above were explicitly framed around finding alternatives as conventional dewormers lose effectiveness[3]. That is a genuine and active area of veterinary parasitology research. It is a research question about herd- and flock-level parasite management, not a green light for dosing a household pet without guidance.
Safer Alternatives for Pet Deworming
If you’re looking to deworm a dog or cat, the evidence-based path is a veterinarian-directed protocol: a fecal test to confirm which parasite is present, followed by an FDA-approved anthelmintic dosed correctly for your pet’s weight and species. If you’re specifically interested in the herbal-alternative angle because of concerns about conventional dewormers, that’s a conversation to have directly with your vet — not a substitution to make on your own with a plant the ASPCA lists as toxic to the animal you’re trying to treat.
FAQ
Can I give my dog wormwood to deworm it?
No controlled study supports a safe or effective dog dose, and the ASPCA lists wormwood as toxic to dogs. This should only be considered under direct veterinary guidance, if at all.
Does wormwood actually work as a dewormer in animals?
In controlled studies, wormwood extracts showed anthelmintic activity in laboratory tests, and a 2009 sheep study reported reduced egg output, but a 2020 sheep study and a 2025 goat study found no significant effect on egg counts in the treated animals[2][3][4]. That evidence is specific to those species and those study protocols.
Is wormwood the same risk for cats as for dogs?
The ASPCA lists both cats and dogs (and horses) as at-risk species for Artemisia toxicity[1].
References
- ASPCA Animal Poison Control Center. Toxic and Non-Toxic Plant List. www.aspca.org/pet-care/animal-poison-control/…
- Mravčáková D, et al. Anthelmintic Activity of Wormwood (Artemisia absinthium L.) and Mallow (Malva sylvestris L.) against Haemonchus contortus in Sheep. Animals (Basel). 2020. pubmed.ncbi.nlm.nih.gov/32013192/…
- Tariq KA, et al. Anthelmintic activity of extracts of Artemisia absinthium against ovine nematodes. Veterinary Parasitology. 2009. pubmed.ncbi.nlm.nih.gov/19070963/…
- Flores-Prado V, et al. In vitro and in vivo anthelmintic activity of Artemisia absinthium against gastrointestinal nematodes of free-grazing goats from Ayacucho, Peru. Journal of Advanced Veterinary and Animal Research. 2025. pubmed.ncbi.nlm.nih.gov/41328231/…
- Merck Veterinary Manual. Toxicoses in Animals From Human Dietary and Herbal Supplements. www.merckvetmanual.com/toxicology/toxicoses-f…
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.
