Ashwagandha for Dogs: Is It Safe, and Does It Work?

Ashwagandha for dogs is sold as a calming herb and, lately, a "healthy aging" one. Short version: the three small dog trials that exist found it well tolerated, and cortisol fell in the two that measured it. All three used one branded root extract, ran 60 days at most, and the extract's maker supplied the product for at least two. Nothing on long-term use in dogs. Below: the studies, side effects and drug interactions, who should skip it, why your 300 mg capsule isn't a dog product, and how to read a pet label.

Is ashwagandha safe for dogs?

Probably, for a healthy adult dog at a pet-label amount, for a couple of months at most. Past that, honestly, nobody has checked.

Open the Merck Veterinary Manual and you'll find one entry, under toxicology, written by a Pet Poison Helpline toxicologist: ashwagandha is "typically well tolerated by animals; however, it can lead to mild GI signs. Treatment is supportive care." We couldn't find a page on it at VCA, PetMD, the ASPCA or the Pet Poison Helpline itself. Chewy's vet-reviewed guide (Angela Beal, DVM, May 2026) puts it plainly: "The safety record of ashwagandha in dogs is thin."

Here's everything we know from dogs: three randomized trials, 12 to 24 dogs each, four weeks to two months, all on the same root extract (KSM-66) at 15 mg per kilogram of body weight once a day. None reported an adverse event. Nothing past 60 days has been studied. For people, the NIH Office of Dietary Supplements says it "appears to be well tolerated" for up to about three months, long-term safety unknown.

Thyroid, liver, pregnancy and drug interactions are the unknowns; each gets a section below. Ask your vet before you start, especially if your dog takes any medication.

What ashwagandha actually is

A shrub root, mostly. Withania somnifera is a small evergreen shrub native to India and Southeast Asia; supplements are usually made from the root, though some include leaf. Ayurvedic medicine has used it for centuries as an "adaptogen," the idea being that it helps the body handle stress. Other names: winter cherry, Indian ginseng (no relation).

Researchers care about compounds called withanolides, though the exact active ingredient isn't settled. Human stress trials used 240 to 1,250 mg a day, with the clearest effect around 300 to 600. A 2022 meta-analysis of 12 of them (1,002 adults) found lower anxiety and stress scores, and rated the certainty of that evidence low.

How did dogs end up on it? Calming-chew makers started adding small amounts to blends with valerian, L-theanine, chamomile and melatonin, and like reishi mushroom for dogs, it gets sold on the word adaptogen more than on dog data.

What the dog studies show about stress

Lower cortisol and lower owner-rated fear and anxiety scores over four weeks, from one trial of 24 dogs.

It's a 2022 randomized trial: dogs described as experiencing stress and anxiety, double-blind, placebo-controlled, 15 mg/kg of standardized root extract (KSM-66) once a day. Versus placebo, the urine cortisol-to-creatinine ratio fell (P = 0.0005), owners' scores on the CBARQ fear and anxiety questionnaire fell (P = 0.03), and Canine Brief Pain Inventory pain scores dropped too. No adverse events were reported.

Caveats, starting with the marketing: sponsored write-ups quote percentage improvements that don't match the published abstract (one is a pain-score number quoted as cortisol), so ignore them. We couldn't check the paper's funding statement, and the extract's maker promotes the study on its own site.

Encouraging, from one extract and one small trial, and not a reason to skip a behavior plan or a vet visit for a dog who's scared of fireworks or can't cope when she's left alone.

What the studies show about aging

Two 60-day trials, one research group, one extract, and everything that moved was a lab value. Nothing on lifespan, cognition or mobility, so "healthy aging" on a label means lab markers, not longer lives.

The main one is a 2024 study of 20 senior Labradors, described as healthy but obese (so, Labradors). Half got KSM-66 root extract at 15 mg per kg with dinner, half a starch placebo. Day 60 cortisol: 1.88 µg/dL on ashwagandha, 2.75 on placebo. Liver enzymes, kidney values and three inflammatory cytokines were lower, antioxidant markers higher, and all 20 finished with no health issues reported.

Now the caveats. The ashwagandha dogs averaged about 10 years old, the placebo dogs almost 15 (the paper doesn't discuss it). How did they act? The behavior questionnaires were never reported. The extract maker gifted the product. Some numbers in the abstract don't match the results.

Same group, 2025: 12 kennel Beagles aged 12 to 15, same extract and dose, 60 days again. Better stool scores, more short-chain fatty acids, lower ALT and AST. Cortisol and behavior weren't measured.

Side effects and drug interactions

In dogs, the only side effect on record is mild stomach trouble ("mild GI signs", per the Merck Vet Manual). The bigger questions (thyroid, liver, her other medications) have barely been studied in dogs.

Watch for vomiting, loose stool or unusual sleepiness; severe sleepiness or shakiness means call the vet. People get mild stomach upset, loose stools, nausea and drowsiness; the drowsiness has a mechanism (in sleep-deprived rats the extract lengthened sleep, and a GABA-receptor blocker cancelled that), so labels say use caution with sedatives and "do not use prior to anesthesia".

Thyroid is the big one, honestly: in 50 adults with mildly underactive thyroids, 600 mg a day for 8 weeks shifted TSH, T4 and T3, and three case reports describe overactive thyroids that cleared after stopping. No dog trial measured thyroid hormones, so a hypothyroid dog on levothyroxine is a genuine unknown.

Liver next. The NIH's LiverTox database rates ashwagandha a "B (likely cause)" of liver injury in people, typically 2 to 12 weeks in, usually mild and gone within 1 to 4 months of stopping. An Indian series of 23 patients included 3 deaths. Denmark banned it for people in 2023 because no safe dose could be set. No liver injury in the dog trials (enzymes actually fell), but small samples, short studies.

Human references list interactions with thyroid hormone, diabetes and blood pressure drugs, immunosuppressants and sedatives; the Merck Vet Manual warns that herbs can change blood levels of prescription drugs.

Which dogs should skip it

Any dog on medication, until her vet clears it, and these groups outright:

• Pregnant, nursing or breeding dogs (possible abortion risk per the Merck Manual; labels agree).
• Dogs with thyroid disease or on levothyroxine.
• Diabetic dogs on insulin, and dogs on blood pressure medication.
• Dogs on immunosuppressants, including many allergy and immune-disease drugs.
• Dogs on sedatives or anxiety meds, or with surgery or a dental coming up (ask the vet when to stop).
• Dogs with liver disease or unexplained high liver enzymes.
• Dogs with cancer: nothing shows it helps against cancer in dogs (lab-dish effects haven't been seen in people, per Memorial Sloan Kettering), and it could interact with the drugs given alongside chemo. Ask the oncologist.
• Puppies and dogs under about a year: no data.

If your dog takes nothing and is healthy, that's the group the studies actually looked at.

Can I give my dog my own 300 mg ashwagandha capsule?

Not a good idea, and the herb isn't the problem. The amount is. A typical human capsule is 300 mg of root extract, taken twice a day.

The dog trials used 15 mg per kg: about 300 mg a day for a 44-pound dog, about 75 mg for a 10-pound one (our arithmetic, not a recommendation). One capsule is the full research dose for a mid-size dog and four times it for a small one, with nobody checking her liver or thyroid.

Gummies are worse, honestly. Sugar-free ones use sugar alcohols like maltitol, sorbitol or erythritol (check every label for xylitol and other sweeteners), and one "ashwagandha complex" gummy packs 100 mcg of vitamin D per gummy. Vitamin D is toxic to dogs at high doses. Chewy's vet-reviewed guide agrees: no human products without vet approval.

A whole bottle, though, means a call to your vet or a pet poison line. Treatment is supportive care, per the Merck Vet Manual.

How much ashwagandha should a dog get?

There's no established dose for dogs; your vet sets it. The one researched amount, 15 mg/kg a day of KSM-66 root extract for 4 weeks to 60 days, isn't a label standard, and most calming chews hold far less per chew.

Labels we checked list 15 to 250 mg of ashwagandha per chew, usually in a blend with valerian, L-theanine, chamomile, L-tryptophan or melatonin. Not one printed a withanolide percentage.

Give the label serving, and don't double it "for a thunderstorm" on a retailer's say-so. Then wait a couple of weeks before you judge it, and tell your vet it's on her list.

US pet supplements fall outside the human supplement law (DSHEA), and the FDA counts any product claiming to treat or prevent a disease as an unapproved animal drug, so "supports a calm mood" is the most a legal label can say. No agency checked the chew for effectiveness before it hit the shelf. We've written up how to check any supplement chew for recalls and a NASC seal.

How to read a pet ashwagandha label

Four things: plant part, extract name, mg per chew, and the seal.

Root-only is what the dog trials used; the leaf carries far more withaferin A, the compound regulators worried about, so "root and leaf" is worth noticing. And with strength running 5% to 35%, "mg of ashwagandha" alone doesn't tell you the dose of active compounds.

That NASC Quality Seal means the National Animal Supplement Council audits the company every two years, tests random products against their labels, and requires caution statements. It's a quality signal, not proof the chew works; a chew without it isn't automatically unsafe. Either way, expect these lines: not for pregnant or nursing animals, caution with sedatives, do not use before anesthesia, ask a vet if the dog is on medication.

If her vet is fine with it, pick a root-only chew with a named extract and a seal, start with the label amount, and watch her stomach and energy. Two weeks of nothing means it probably isn't the chew that's going to fix a scared dog.

Photos don't show diagnosed cases.