Valerian

botanicalvalerenic acid

What is it

Valerian (Valeriana officinalis) is a perennial plant native to Europe and Asia, now naturalized in North America, with a characteristically unpleasant odor. Its roots, rhizomes, and stolons have been used since ancient Greece and Rome as a mild sedative and sleep aid; Hippocrates documented its use and Galen prescribed it for insomnia in the 2nd century. More than 250 species exist in the genus, but Valeriana officinalis is the primary medicinal species used in the United States and Europe.

How it works

No scientific consensus exists about which compounds in valerian are active. Volatile oils containing valerenic acids, sesquiterpenes, and the iridoid valepotriates are sometimes used for standardization, but it is likely that multiple constituents contribute either independently or synergistically rather than any single agent producing the effect. The leading mechanistic proposal involves modulation of gamma aminobutyric acid (GABA), the brain's main inhibitory neurotransmitter. In vitro studies suggest valerian extract may cause GABA release from nerve endings while blocking GABA reuptake, and valerenic acid inhibits the enzymes that destroy GABA. Valerian extracts also contain GABA itself in sufficient amounts to theoretically have effects, though whether GABA from the extract crosses the blood-brain barrier remains unknown. Glutamine present in aqueous (but not alcohol) extracts may cross the barrier and convert to GABA in the brain. Constituent levels vary significantly based on harvest timing and processing, creating marked variability between preparations.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Sleep onset and quality

Grade C

Moderate evidence

A systematic review identified nine randomized, placebo-controlled, double-blind trials. Three earned the highest quality ratings. One trial in 128 volunteers using 400 mg aqueous valerian extract showed statistically significant subjective improvements in time to fall asleep, sleep quality, and nighttime awakenings versus placebo, particularly in self-identified poor sleepers. A trial in 121 participants with documented nonorganic insomnia using 600 mg standardized LI 156 for 28 days demonstrated decreased insomnia symptoms across all assessment tools versus placebo. However, the reviewers concluded these nine studies are not sufficient for determining the effectiveness of valerian for sleep disorders due to methodological limitations including lack of blinding verification, inadequate sample size calculations, minimal control of prebedtime variables, and unvalidated outcome measures.

Comparison with prescription sedatives

Grade C

Moderate evidence

A randomized, double-blind trial compared 600 mg valerian extract (LI 156) to 10 mg oxazepam (a benzodiazepine) in 75 participants with documented insomnia over 28 days. Both groups showed equivalent sleep quality improvement, though the valerian group reported fewer side effects. The study design could not, however, formally demonstrate equivalence.

Objective sleep architecture (polysomnography)

Grade C

Moderate evidence

A polysomnographic crossover study in 16 insomnia patients using 600 mg valerian (LI 156) versus placebo found valerian had no effect on 14 of 15 objective and subjective sleep measurements, with the only positive finding being decreased slow-wave sleep onset (13.5 versus 21.3 minutes with placebo).

Anxiety

Grade D

Mixed evidence

Valerian has traditional and ongoing use for nervousness and anxiety, but rigorous controlled clinical trials specifically for anxiety disorders are limited compared to its sleep evidence.

Gastrointestinal spasms, epilepsy, and ADHD (traditional uses)

Grade F

Limited evidence

Beyond sleep, valerian has been used traditionally for gastrointestinal spasms, epilepsy, and ADHD. Scientific evidence is not sufficient to support the use of valerian for these conditions.

5 commercial forms

Valerian root extract (capsules)

Standardized to specific bioactive content; varies by manufacturer.

Most common consumer form. Reduces the strong odor associated with the raw root.

LI 156 (standardized preparation)

Standardized German preparation; used in many positive clinical trials.

The most-studied standardized form. 600 mg before bed is the trial-tested dose.

Valerian tincture (liquid alcohol extract)

Different bioactive profile than aqueous extracts; lacks glutamine.

Traditional liquid form. Mixed with water before bed. Strong taste and odor.

Valerian root tea

Aqueous extract; lower potency than capsules.

Traditional preparation. The aqueous form retains glutamine which may convert to GABA in the brain.

Combined valerian + hops

Common combination; one trial of valerian + hops (60 mg + 30 mg) showed no significant sleep improvement.

Popular in commercial sleep products. Limited evidence the combination outperforms valerian alone.

Dosage

There is no standard dose. Trials of standardized valerian root preparations have used 400 mg of aqueous extract, 600 mg of LI 156 (a German standardized preparation), 450 to 900 mg, and similar amounts taken 30 to 60 minutes before bed. Higher doses (900 mg) have not shown additional benefit and may cause more next-day grogginess. Commercial products typically provide 300 to 600 mg per dose.

When and how to take it

Take valerian 30 to 60 minutes before bed. Most positive sleep trials used a single bedtime dose; splitting throughout the day for daytime anxiety is also done but with less robust evidence. Avoid taking other sedatives or alcohol the same evening. Higher doses (900 mg) have caused next-day grogginess in some studies, so 400 to 600 mg is typically a better choice if you have morning obligations. Effects may build over 2 to 4 weeks of consistent nightly use in some trials, though acute single-dose effects are also reported. The strong unpleasant odor is the main practical complaint; capsules with enteric coating reduce burping.

Safety

Few adverse events are described in clinical trial reports. Most commonly reported effects in trials are headaches, dizziness, pruritus, and gastrointestinal disturbances, though similar effects also occurred with placebo. One study noted increased morning sleepiness after 900 mg doses. Investigators concluded 600 mg of LI 156 produced no clinically significant effects on reaction time, alertness, or concentration the following morning. Long-term safety data are lacking. Several case reports describe adverse effects, though one involved a suicide attempt with massive overdose where valerian attribution remains unclear. Valepotriates demonstrated cytotoxic activity in vitro but were not carcinogenic in animal studies. Valerian is sold as a dietary supplement in the United States and regulated as a food, so premarket FDA evaluation is not required and lot-to-lot composition may vary considerably.

Who should be cautious

Pregnant or nursing women should not take valerian without medical consultation, as fetal and infant risks remain unevaluated. Children younger than 3 years should not take valerian due to unassessed risks. Individuals taking valerian should recognize the theoretical possibility of additive sedative effects from alcohol or sedative drugs including barbiturates and benzodiazepines. People scheduled for surgery should stop valerian several days beforehand due to additive sedation with anesthesia.

Interactions

Valerian might produce additive therapeutic and adverse effects when combined with other sedatives and CNS depressants. Specific examples include benzodiazepines (such as Xanax, Valium, Ativan, Halcion), barbiturates and CNS depressants (such as phenobarbital, morphine, propofol), and dietary supplements with sedative properties (St. John's wort, kava, melatonin). Individuals taking these medications or supplements should consult healthcare providers about valerian use. Although valerian has not been reported to influence laboratory tests, this has been insufficiently studied.

Frequently asked questions

Does valerian actually work for sleep?⌄

Evidence is mixed. The Office of Dietary Supplements summary of the clinical literature concludes that the nine main randomized trials are not sufficient for determining valerian's effectiveness due to methodological limitations. Some trials show subjective improvements, particularly in self-identified poor sleepers, but objective polysomnography typically shows little to no effect. Effects, when present, are modest.

How fast does valerian work?⌄

Some users notice effects within 30 to 60 minutes of a bedtime dose; others find effects build over 2 to 4 weeks of consistent use. The 28-day trials showed greater differences between day 14 and day 28, suggesting cumulative benefit.

Will valerian make me groggy in the morning?⌄

At 600 mg of standardized extract, controlled studies found no significant next-morning effects on reaction time, alertness, or concentration. At 900 mg, one study noted increased morning sleepiness. Lower doses (400 to 600 mg) are typically a better balance of sleep effect and next-day function.

Can I take valerian with sleeping pills?⌄

Not without medical guidance. Valerian may produce additive sedative effects with benzodiazepines, barbiturates, and other CNS depressants. The combination is not necessarily dangerous but the cumulative effect can be stronger than expected.

Why does valerian smell so bad?⌄

Valerian's characteristic unpleasant odor (often compared to old gym socks or stale cheese) comes from isovaleric acid and other volatile compounds in the root. Cats find the smell similar to certain attractive feline pheromones. Capsules and enteric-coated tablets minimize the odor for human users.

References

NIH ODS: Valerian Health Professional Fact Sheet — Office of Dietary Supplements link
Wikidata: Valeriana officinalis — Wikidata link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.