What is valerian root? A plain guide

Valerian root is the dried root and rhizome of Valeriana officinalis, a flowering plant native to Europe and parts of Asia. People have used preparations of it for centuries, and today it's sold as loose or bagged tea, tincture drops, and capsules — most often a concentrated extract, marketed for winding down before bed. The research behind that marketing is thinner than the marketing itself; see valerian root benefits: what the research does and doesn't show for what trials have actually found.

Where it comes from

Valeriana officinalis grows wild across Europe and temperate Asia and has naturalized in North America. The part used in supplements is the root and rhizome — the underground stem — harvested and dried, not the small pink or white flowers that grow above ground. Written references to valerian as a calming, sleep-associated herb go back to ancient Greece, and the plant has held official status in European and American pharmacopeias at various points over the last two centuries.

What's actually in it

Valerian root's chemistry includes a volatile oil, sesquiterpenes including valerenic acid, and a separate class of compounds called valepotriates. Valerenic acid gets the most research attention: in laboratory studies, it's been shown to slow the breakdown of GABA, a calming brain chemical, which is the leading theory for how valerian might work (PMID 10411208). That's laboratory-level evidence about a mechanism, not proof that a given capsule produces a noticeable effect in a person — see the benefits page linked above for what's actually been tested in people.

Forms it's sold in

Three forms cover most of what's on shelves: dried root for tea, liquid tincture, and capsules or tablets made from a concentrated extract. Extracts are often standardized to a percentage of valerenic acid — commonly 0.8% — so that two bottles labeled the same strength contain a comparable amount of that one compound, at least in theory. A 2004 lab analysis of 14 commercial valerian products found real variation between what was printed on the label and what the product actually contained (PMID 15367385), which is a reason to expect some inconsistency across brands regardless of what the label states.

Why it smells the way it does

Fresh valerian root doesn't have much odor. The strong smell people describe as sweaty, musty, or like aged cheese develops as the root dries and its volatile compounds — isovaleric acid among them — form and concentrate. That's a normal feature of the dried herb, not a sign it's gone bad.

What people use it for

Most people searching for valerian root are looking for something to help with sleep or nervousness before a stressful event — that's the traditional use, and it's the reason most clinical trials have tested it. Whether the trials back that up is a separate question from what the plant contains or how it's sold, and it gets a page of its own: valerian root benefits: what the research does and doesn't show.

Questions people ask

Is valerian root addictive?

Case reports describe withdrawal symptoms, including delirium and in one case cardiac complications, after people stopped valerian abruptly following prolonged, high-dose use (PMID 9820254, PMID 32576405). That's documented physical dependence in specific, published cases — not the same thing as classic drug addiction, and it appears uncommon — but it's a reason not to stop long-term, high-dose use suddenly. More in valerian root side effects.

What does valerian root smell like?

Most people describe it as sweaty, musty, or like aged cheese — caused by isovaleric acid and other compounds that form as the root dries (PMID 10411208).

What does valerian root taste like?

Brewed as tea, it tastes roughly as it smells: earthy, musty, and slightly bitter. Capsules avoid the taste entirely, which is why many people who dislike the tea choose that form instead.

How does valerian root work?

The leading laboratory theory centers on valerenic acid, one of its compounds, which has been shown to slow the breakdown of GABA, a calming brain chemical (PMID 10411208). That's a plausible mechanism identified in lab research, not confirmation that it produces a reliable effect in people — see valerian root benefits: what the research does and doesn't show for the human trial evidence.

Can dogs or cats have valerian root?

This page and its citations cover valerian as a human supplement. Dosing for animals isn't the same as dosing for people, and none of the research here was done in pets — ask a veterinarian before giving any human supplement to an animal.

Where does valerian root grow, and can I grow it myself?

It grows wild across Europe and temperate Asia and is cultivated commercially in several countries. Home gardeners in temperate climates can grow it too, though the details of planting and harvesting are a gardening question this page doesn't cover.

Related reading: valerian root benefits: what the research does and doesn't show, how much valerian root should you take a day?, and how to choose a good valerian root.