Yes, yarrow (Achillea millefolium) is toxic to dogs. The ASPCA lists it as a toxic plant for dogs, cats, and horses. The good news is that yarrow poisoning is rarely life-threatening. Most dogs recover fully, especially with prompt care. But the plant contains several irritating compounds that can make your dog noticeably sick if they eat enough of it.
What Makes Yarrow Toxic
Yarrow contains three groups of compounds that cause problems for dogs: glycoalkaloids (specifically one called achillein), monoterpenes, and sesquiterpene lactones. In practical terms, these substances irritate the digestive tract and can affect the nervous system at higher doses. All parts of the plant carry these compounds, including the flowers, leaves, and stems.
The level of toxicity is considered mild to moderate. A dog that nibbles a small amount of yarrow will likely experience less severe symptoms than one that eats a large quantity. Body size matters too: a Chihuahua eating the same amount as a Labrador will have a harder time.
Symptoms to Watch For
The most common signs of yarrow ingestion in dogs are gastrointestinal: vomiting, diarrhea, drooling, and loss of appetite. These typically show up within a few hours of eating the plant.
In larger amounts, yarrow can cause more concerning symptoms. Dogs may become lethargic or uncoordinated. Some dogs develop skin irritation from direct contact with the plant, since the sesquiterpene lactones in yarrow are known to cause contact reactions in sensitive individuals. If your dog has been rolling in or chewing on yarrow and you notice redness or itching around their mouth or skin, that’s likely why.
Increased urination is another reported sign. In rare cases involving very large amounts, dogs may experience a drop in blood pressure or changes in heart rate, though this is uncommon with typical garden or trail exposure.
Extra Risk for Pregnant Dogs
Yarrow has a long traditional history of use as a substance that stimulates uterine contractions. Research in pregnant rats found that yarrow exposure was associated with reduced fetal weight and increased placental weight, even at doses that weren’t toxic to the mother. While the study didn’t find evidence of miscarriage at the dose tested, the researchers concluded that yarrow should be considered unsafe during pregnancy until more is known. If your dog is pregnant, keep her away from yarrow entirely.
What to Do After Ingestion
If you see your dog eating yarrow, try to estimate how much they consumed and note the time. For small nibbles, monitoring at home may be sufficient, but calling your vet or the ASPCA Animal Poison Control Center (888-426-4435) is always a smart move.
For larger amounts eaten recently (within the past couple of hours), a veterinarian may induce vomiting to remove the plant material before more of it gets absorbed. This is only safe when done under veterinary supervision, since inducing vomiting incorrectly can cause aspiration into the lungs. Activated charcoal is another common tool vets use to bind remaining toxins in the gut and prevent further absorption.
Most dogs with mild symptoms recover within 24 to 48 hours with supportive care, which may include fluids to prevent dehydration from vomiting or diarrhea. Severe cases are rare.
Where Dogs Encounter Yarrow
Yarrow is a widespread wildflower found across North America, Europe, and Asia. It grows in meadows, along roadsides, in parks, and in home gardens, where it’s popular for its drought tolerance and clusters of small white or yellow flowers. The feathery, fern-like leaves sit on slightly fuzzy green stems, and the plant typically reaches two to three feet tall.
Dogs most commonly encounter yarrow during walks on trails or in fields, or in yards where it grows as a ground cover or ornamental. Some pet owners also come across yarrow in herbal supplements marketed for dogs. While yarrow has been used in traditional herbal medicine for centuries, there are no quality clinical studies establishing a safe dose for dogs. The lack of reliable safety data makes herbal yarrow products a gamble.
Don’t Confuse Yarrow With Poison Hemlock
One important reason to know what yarrow looks like: it can be confused with poison hemlock, a plant that is far more dangerous. Both have clusters of small white flowers and delicate-looking leaves. But the differences are significant once you know what to look for.
- Height: Yarrow tops out around two to three feet. Poison hemlock can reach five to ten feet when fully grown.
- Leaves: Yarrow leaves are thin, frilly, and fern-like. Hemlock leaves are broader, flatter, and shaped more like parsley.
- Stems: Yarrow stems are green and slightly fuzzy. Hemlock stems are smooth and hairless, often with distinctive purplish-red blotches.
- Flower shape: Yarrow flowers form flat-topped clusters but not true umbels. Hemlock flowers branch out from a single point like the ribs of an umbrella.
If your dog eats a plant you suspect might be poison hemlock rather than yarrow, that’s a veterinary emergency. Hemlock poisoning can be fatal within hours.
Keeping Your Dog Safe
If yarrow grows in your yard, consider removing it or fencing it off, especially if your dog tends to graze on plants. When hiking, keeping your dog on a leash through meadows and field edges reduces the chance of them snacking on yarrow or its more dangerous look-alikes. Training a reliable “leave it” command is one of the best long-term tools for preventing plant ingestion on walks.
For dogs that have already eaten yarrow and are showing symptoms, keep them hydrated and avoid offering food until the vomiting settles. Save a sample of the plant if you can, since having it on hand helps your vet confirm what your dog ate and rule out more toxic species.