Is Yarrow Toxic to Pets? Achillea Millefolium Garden Risk

Last updated: May 16, 2026

Is Yarrow Toxic to Pets? The Quick Answer

Yes, yarrow is toxic to pets. Achillea millefolium is on the ASPCA toxic plant list for both dogs and cats, with the toxic compounds identified as achilleic acid, alkaloids, and small amounts of thujone (a neuroactive compound also found in sage and wormwood). The toxicity sits in the mild-to-moderate range. A nibble of yarrow leaves usually produces drooling, vomiting, and mild diarrhea; a sustained graze, particularly by a cat or a small dog, can produce more pronounced GI signs, sometimes lethargy, and rarely CNS effects from the thujone fraction. Yarrow is widely planted in herb gardens, wildflower meadows, lawn-wildflower mixes, and as a long-blooming perennial, so the plant is far more accessible than its toxic status suggests.

The pet-owner confusion is understandable. Yarrow is also a medicinal herb with a long human history (the genus name Achillea references Achilles using yarrow to treat soldiers’ wounds). Modern herbalism still uses yarrow tea and tinctures for menstrual support, fever, and minor wound care under controlled doses. Pets do not benefit from these uses, get no controlled dosing from foraging on a plant in the yard, and have a different metabolic relationship to the active compounds. This guide walks through the biology, the chemistry, the species likely to show up in pet yards, and what to do when a pet has eaten yarrow.

Meet Achillea Millefolium, the Feathered Wildflower

Common yarrow is a hardy perennial native to temperate Eurasia, naturalized across North America, and now grown ornamentally worldwide. The plant grows two to three feet tall, with feathery finely-divided leaves arranged along upright stems and flat-topped clusters of small white (sometimes pink, yellow, or red in cultivars) flowers throughout summer. The “millefolium” species name means “thousand-leaved,” referring to the finely dissected leaf structure that distinguishes yarrow from most other roadside wildflowers. The plant spreads by rhizomes and seed and tolerates drought, poor soil, and full sun.

Yarrow appears in three main contexts that pet owners encounter: wildflower meadows and prairie restorations (where it is often a dominant species), lawn-wildflower mixes sold as eco-friendly alternatives to monoculture turf, and ornamental perennial borders (where named cultivars in pink, yellow, peach, and red are valued for long bloom and cut-flower use). All three contexts give pets potential access. The leaves are accessible at dog-grazing height; the flowers are accessible to curious cats who jump into garden beds.

The Toxic Compounds in Yarrow

Yarrow contains several biologically active compounds. Achilleic acid (an acid named for the genus) and related sesquiterpene lactones produce GI irritation and can drive vomiting and diarrhea. The plant also contains volatile oils with thujone and small amounts of camphor, both neuroactive at higher doses. Thujone is the same compound implicated in absinthe lore and is found in sage and wormwood; in concentrated form it can produce CNS depression, tremors, or seizures, though pet-side toxicity from yarrow rarely reaches those concentrations. The plant also contains coumarin compounds that can theoretically affect blood clotting in very large doses, though clinically meaningful coagulation issues from yarrow ingestion in pets are uncommon.

The ASPCA listing reflects the cumulative toxicity rather than a single dramatic compound. The risk profile is “mild-to-moderate GI upset, occasional CNS signs in larger doses.” Cats are slightly more sensitive than dogs because of their reduced ability to metabolize certain plant secondary compounds, though both species can show clinical signs from sustained ingestion.

Symptoms of Yarrow Ingestion

Early signs are GI: drooling, lip-smacking, vomiting, and soft stool or diarrhea, usually within an hour or two of ingestion. Many pets dislike the strong herbal taste of fresh yarrow and back off after a single mouthful; the cases that progress are usually those where a bored or curious pet kept eating. Depression, lethargy, and reduced appetite can follow. Ataxia (uncoordinated movement), tremors, or unusual disorientation are uncommon but consistent with the thujone fraction at higher doses; these signs indicate a more serious exposure that warrants prompt veterinary attention.

Skin contact with yarrow can produce mild dermatitis in some pets and humans, though it is a much less common pathway than ingestion. Owners who handle yarrow extensively (gardening, cut-flower work) sometimes develop a contact rash; pets in similar gardens occasionally show muzzle or paw irritation. The symptoms generally resolve on their own once contact stops.

What to Do If Your Pet Ate Yarrow

Step one. Remove access. Take the pet away from the yarrow patch and check the mouth for plant matter. Step two. Identify the plant if possible; photograph it for the vet team. Yarrow is identifiable by the feathery leaves and flat-topped flower clusters. Step three. Estimate the amount eaten. A leaf or two is a different conversation than a meal-size graze. Step four. Call. Your veterinarian, the ASPCA Animal Poison Control Center at 888-426-4435, or the Pet Poison Helpline at 855-764-7661 will triage based on species, weight, amount, time elapsed, and any current medications.

Do not induce vomiting at home. Yarrow is bitter and irritating; bringing it back up through an already inflamed esophagus is rarely helpful. Let the vet team direct decontamination decisions, which may include activated charcoal in some windows, IV fluids, antiemetics, and observation. For the unusual case of CNS signs (tremors, ataxia, seizures), prompt clinic transport for supportive care is the right move. Most yarrow exposures recover with home monitoring or short-course supportive care.

Cat-Specific Concerns

Cats are slightly more sensitive than dogs to yarrow, in part because of the species’ reduced ability to glucuronidate certain plant compounds. A cat seen chewing yarrow leaves warrants a same-day vet call, even if the cat seems fine. Cats also tend to ingest plants in stealth, so by the time you notice the chewing the amount may already be larger than expected. Indoor cats with garden access are at highest risk; cats with cut-flower yarrow arrangements indoors are at theoretical risk if they chew the stems or flowers.

If you have a cat who chews on indoor flower arrangements, avoid yarrow as a cut flower in the house. The same applies to buttercups, anemones, and several other cut-flower-friendly but cat-toxic species. The general principle: any cut flowers brought indoors should be checked against the ASPCA list before placing where the cat can reach.

Yarrow in Wildflower Meadows and Lawn Mixes

Yarrow is a common component of wildflower seed mixes sold for “pollinator” or “eco-lawn” use, and it spreads aggressively in established meadows. Households that converted a portion of lawn to a wildflower meadow may have substantial yarrow without realizing it; the feathery leaves blend into the green of mixed plantings until the flat white flower heads appear in summer. For dog yards, this is a real exposure source. For cat households, outdoor cats with meadow access are similarly exposed.

If you discover yarrow in a meadow planting and want to manage exposure, the realistic options are: hand-pull or dig out the rhizome clumps in the immediate dog-access zone, fence off a no-pet area where yarrow can persist for the pollinators, or accept the exposure and watch the pets carefully during peak summer when the plant is most attractive to graze. Replacement plantings of other pollinator-friendly perennials (coneflowers, bee balm, asters) maintain the wildflower function without the toxicity concern.

Identifying Yarrow in Your Yard

Yarrow is most easily identified by the combination of upright stems two to three feet tall, finely divided feathery leaves that look almost fern-like, and flat-topped clusters of small white flowers arranged like a crowded umbrella. Crush a leaf and the strong herbal-medicinal scent (slightly sage-like, slightly camphor-like) is distinctive. Cultivar yarrows in pink, yellow, peach, and red are common in perennial borders and have the same leaf and overall plant form, just different flower colors.

Look-alikes include Queen Anne’s lace (Daucus carota, with broader leaflets and umbrella-shaped flower clusters that have a distinctive purple central spot), poison hemlock (Conium maculatum, with broader leaflets and a purple-spotted hollow stem, far more dangerous), and various Apiaceae family relatives. Misidentifying yarrow as Queen Anne’s lace is the more common error; misidentifying poison hemlock as yarrow is a much more dangerous error and a reason to confirm species before letting pets near “yarrow-like” plants.

Yarrow vs Other Toxic Garden Herbs

Yarrow shares the herb-garden toxic-plant category with several relatives. Sage and its dog-side cousin contain thujone in higher concentrations and are ASPCA toxic. Tarragon contains estragole and is on watch lists. Marjoram is a milder concern. Ragwort in pasture is a much more serious case with hepatotoxic pyrrolizidine alkaloids. Recognizing the herb-garden category helps when a multi-plant exposure is suspected.

For broader garden context, buttercups and anemones are common ornamentals on the same toxic list. The pet-safe alternatives for similar visual function are covered in our pet-safe garden plants guide, which lists species that fill the cottage-garden niche without the toxicity concern.

Yarrow as Human Herbal Medicine

Yarrow has a long human medicinal tradition. Its species name comes from Achilles, whose troops in Greek myth were treated with yarrow for wounds. Modern herbalism still uses yarrow tea, tincture, and topical preparations for menstrual support, mild fever, indigestion, and minor wound care. Controlled doses by adult humans tolerating the bitter taste are generally well-tolerated, though pregnant individuals are advised to avoid it because of historical association with menstrual stimulation.

None of this human-side benefit translates into pet recommendations. A pet foraging on a yarrow plant gets no medicinal benefit, no controlled dose, and a meaningful chance of GI upset or worse. Herbal products marketed for pets occasionally include yarrow extract; use only under veterinary direction and only at the manufacturer’s recommended dose. The pet-side risk-benefit calculation is very different from the human-side calculation.

Pet-Safe Yard Setup

If you want pollinator-friendly perennials without the yarrow toxicity, several alternatives fill similar functional niches. Coneflowers (Echinacea, considered safe in routine garden quantities), bee balm (Monarda, generally safe), asters (most species safe), goldenrod (safe), and milkweed (specific species considerations apply) all support pollinators and look right at home in mixed border or meadow plantings. Our pet-safe garden plants guide covers the broader inventory.

For pickup-day prep, our adopt-a-cat hub and adopt-a-dog hub include yard-audit checklists. Identifying yarrow patches and either fencing them or removing them is part of the audit. New pet owners who skip the audit sometimes spend the first months chasing the question of “which plant gave my pet GI upset this time” without realizing yarrow was the culprit.

Vet Routing and Final Notes

Yarrow sits in the mild-to-moderate toxicity tier. Most pet exposures end with home monitoring or a single clinic visit for supportive care. The cases that escalate involve sustained ingestion in cats or small dogs, exposure in pets already on medications that load the liver or kidneys, and the rare CNS-sign case from a large thujone dose. Save your veterinarian’s number, the ASPCA Animal Poison Control Center at 888-426-4435, and the Pet Poison Helpline at 855-764-7661 in your phone for the moments you need them.

If you discover yarrow in your yard or local meadow and want to plan around it, the immediate yard zone is what matters most for daily exposure management. Off-site exposures during walks are less frequent but still worth recognizing, especially in late summer when yarrow blooms are obvious and tempting to a curious dog.

Frequently Asked Questions

Is yarrow toxic to dogs and cats?

Yes. The ASPCA lists Achillea millefolium as toxic to both dogs and cats, with toxic compounds including achilleic acid, alkaloids, and thujone. The toxicity is mild-to-moderate, presenting most often as GI upset (drooling, vomiting, diarrhea).

My dog ate yarrow flowers. What should I do?

Pull the dog away from the plant, check the mouth for any visible material, and call your vet or a poison-control line. Most cases respond to supportive care, but estimating the amount and watching for vomiting, lethargy, or unusual behavior over the next twenty-four hours is important.

Can I use yarrow as an herbal remedy for my pet?

Not without veterinary direction. Yarrow has human medicinal uses but the pet-side risk profile is different. Random foraging gives no controlled dosing and increases the chance of GI upset or thujone-related CNS effects. Use vet-directed products only.

How do I tell yarrow apart from Queen Anne’s lace?

Yarrow has finely divided feathery leaves that look fern-like. Queen Anne’s lace has broader more-obvious leaflets and a distinctive single purple spot in the center of the flat flower cluster. Both grow in similar habitats. Crushing a yarrow leaf releases a strong herbal scent.

Is yarrow in lawn-wildflower mixes safe for my dog?

No, the same toxicity concerns apply whether the yarrow is in a meadow, wildflower mix, ornamental border, or pasture. If you discover yarrow in a planted lawn mix and have dogs with yard access, consider hand-pulling the plants from the immediate dog zone or fencing pet access away.