Valerian Root Side Effects in Dogs: What the Nervous System Actually Does With It

By Neil S. Mittelman, DVM, DACVIM (LAIM, Neurology)

✓ Medically reviewed by Neil S. Mittelman, DVM, DACVIM (LAIM, Neurology) — August 6, 2026 For general education — not a substitute for veterinary care.

Calming & Anxiety · August 12, 2026 · 6 min read

Valerian calms by nudging GABA signaling in the CNS, and that mechanism is exactly why sedation, not magic, is the honest expectation.

Is valerian root actually safe for a dog’s nervous system, or are owners trading one problem for a groggier one?

I get asked this most often by owners who’ve already tried a calming chew from the pet aisle and noticed their dog seems “off” the next morning — a little wobbly on the stairs, slower to react to the doorbell, sleeping through breakfast. That’s not a coincidence. Valerian root’s calming effect and its side effects come from the same mechanism, and as a neurologist, I think owners deserve to hear that plainly instead of getting a marketing gloss about “natural relaxation.”

What is valerian root actually doing in a dog’s CNS?

Valerian’s reputation as a sedative isn’t folklore. The compounds in the root — valerenic acid among them — interact with GABA-A receptor activity, the same inhibitory signaling system that benzodiazepine sedatives work through in mammals, dogs included. GABA is the brake pedal of the central nervous system. When you press harder on that brake, you get calm. Press too hard, or press it on a dog with an already-slow metabolism, and you get sedation that outlasts the storm or the fireworks you were treating in the first place.

This is the gap I want owners to sit with: a calming herb that works on CNS inhibitory signaling is not a wellness add-on, it’s a pharmacologically active substance, and it should be dosed and timed with that in mind.

What side effects actually show up, and in which dogs?

The side effects owners report with valerian root cluster predictably around that GABA-ergic mechanism: drowsiness that runs longer than expected, mild ataxia (a wobbly, uncoordinated gait), and occasionally GI upset — soft stool or reduced appetite — from the herb itself or from whatever carrier it’s delivered in. None of that is exotic pharmacology; it’s the expected downstream of turning up CNS inhibition in an animal that’s smaller and metabolizes drugs faster, pound for pound, than we do.

The dogs I worry about most are the ones already on other CNS-active medications — trazodone, gabapentin, a benzodiazepine for seizure management — because valerian’s GABA activity can stack with those drugs rather than simply adding to them. A senior dog with reduced liver clearance is a second group I flag every time. Their bodies don’t clear sedatives at a young dog’s pace, so a dose that reads “mild” in a healthy adult can sit around long enough to affect gait and alertness into the next day.

I had a fourteen-year-old dachshund in for a lameness recheck a few winters ago whose owner mentioned, almost in passing, that he’d started a valerian-based calming chew for the dog’s noise sensitivity around the holidays. The dog wasn’t lame — he was ataxic, dragging his rear toes slightly and slower to rise, and it had started within days of the new chew. We stopped the supplement, and the gait normalized over the following week. That’s one dog, not a trial, and I’m not presenting it as a general outcome. But it’s exactly the kind of presentation — new hindlimb weakness or wobbliness in an older dog on a new “calming” product — that should send an owner back to the label before it sends them to a neurology workup.

How does valerian compare to the other calming ingredients on the label?

Valerian tends to get lumped in with chamomile, L-theanine, and ashwagandha on calming-chew labels, but the evidence base isn’t uniform across those four, and neither is the mechanism. Chamomile’s calming reputation is grounded mostly in preclinical work and long traditional use rather than robust clinical trials — as one review of chamomile’s role in anxiety and stress notes, “for the remaining species, evidence is derived mainly from preclinical studies or traditional use,” according to a review in Biomedicines. Ashwagandha has somewhat firmer human data behind it: a systematic review in Cureus “analyzed multiple RCTs and concluded that ashwagandha has a moderate positive impact on stress reduction and cognitive performance.” L-theanine’s human evidence is narrower still — a review in Molecular Psychiatry found benefit “except for one study on psychotic anxiety (SMD = 0.54; 400 mg/day for 8 weeks).”

None of that evidence was generated in dogs, and I want to be direct about why that distinction matters clinically. A moderate effect size in a human RCT tells you the compound does something to a human nervous system at a stated human dose; it does not tell you the dose, timing, or safety margin for a 22-pound terrier. Extrapolating human pharmacology onto a dog’s body weight and metabolism is the single most common mistake I see in how these ingredients get marketed.

When is a chamomile or theanine formula a better first move than valerian?

If I’m advising an owner on a first-line calming approach for ordinary noise sensitivity or travel stress, I generally steer them toward chamomile or L-theanine before valerian, not because valerian doesn’t work, but because its sedative ceiling is higher and its interaction risk with other CNS drugs is more consequential. A dog who’s already reactive to sound doesn’t need a compound with a wide range between “took the edge off” and “wobbly and slow to respond.” If your household’s dog is on any other sedative, anticonvulsant, or anti-anxiety medication, that’s a conversation for your veterinarian before you add valerian at all, full stop — not because the herb is uniquely dangerous, but because CNS-active substances don’t stack the way owners assume.

Our guide to the Best Calming Supplement for Dogs scores several formulas on exactly this kind of ingredient-by-ingredient rubric, and it’s a useful next stop if you’re comparing labels. For storm-specific anxiety specifically, we also cover what actually helps in My Dog Is Anxious During Thunderstorms.

I still think about a border collie I saw for an unrelated orthopedic issue whose owner had layered a valerian tincture on top of an existing trazodone prescription for separation anxiety, without telling either prescriber about the other. The dog was profoundly sedate at rest, barely rousing for the exam, heart rate low-normal, nothing acutely dangerous on that visit but clearly over-medicated. We simplified the regimen back down to one CNS-active product at a time, and the owner’s fear — that pulling the valerian would bring the anxiety roaring back — didn’t hold up once we gave the trazodone room to work on its own. The lesson wasn’t that valerian is bad. It’s that nobody was tracking the total CNS load that dog was carrying.

So what’s the actual takeaway on valerian root?

Support and treatment are not the same claim, and valerian root sits on the support side of that line. It can nudge a mildly anxious dog toward calmer behavior through a real, describable mechanism on GABA signaling — that’s not nothing. But it is not a treatment for an anxiety disorder, it is not risk-free in combination with other sedatives, and it is not dosed the same way twice across every product on a shelf. If your dog needs more than an occasional noise-sensitivity nudge, that’s a conversation about a diagnosis and a prescription plan, not a supplement aisle decision.

Watch for drowsiness that outlasts the trigger, any wobbliness in gait, and GI changes after starting a valerian-containing chew, and stop the product if you see them. If your dog is a senior, has liver disease, or takes any other CNS-active medication, loop your veterinarian in before you start, not after.

If you’re building out a broader supplement routine for an aging or anxious dog, our guides to the Best Joint Supplement for Dogs and Best Probiotic for Dogs use the same evidence-first scoring approach.