Valerian root has moderate evidence supporting its use for anxiety, though the results are more promising for mild, situational stress than for clinical anxiety disorders. Several controlled trials show it can reduce anxiety scores and stress reactivity at doses between 100 and 600 mg per day, with effects appearing anywhere from one hour to four weeks depending on the dose and situation.
That said, valerian is not a replacement for established anxiety treatments. It occupies a middle ground: more than placebo in several trials, but without the large, rigorous studies that would make it a first-line recommendation. Here’s what the evidence actually shows.
How Valerian Affects the Brain
Valerian root contains a compound called valerenic acid that acts on the same brain receptors targeted by benzodiazepines (medications like Valium and Xanax). These receptors respond to GABA, a neurotransmitter that slows down brain activity. When valerenic acid activates GABA receptors, it increases chloride currents in brain cells, which has a calming, sedative effect. The mechanism is genuinely similar to prescription anti-anxiety medications, just weaker in potency.
Valerian also appears to influence serotonin pathways. Animal studies show it increases both GABA and serotonin expression in the brain’s memory and emotion centers, which may explain why it affects both sleep and anxiety rather than just one or the other.
What the Clinical Trials Show
The anxiety evidence comes from several small but positive trials. In one four-week study, 300 mg per day of valerian extract (split into three doses) produced measurable anti-anxiety effects. A separate trial found that 600 mg per day for just one week reduced both psychological and physical stress responses in healthy adults under stress conditions. For acute, situational anxiety, a single 100 mg dose given one hour before dental surgery reduced anxiety in patients facing the procedure.
Other trials have tested valerian in more specific populations. A dose of 530 mg per day for four weeks reduced anxiety in HIV-positive patients dealing with medication side effects. For premenstrual anxiety specifically, 1,260 mg per day taken for seven days during three consecutive menstrual cycles was effective.
One particularly notable comparison: a randomized, double-blind trial pitted valerian directly against oxazepam, a benzodiazepine prescribed for anxiety and insomnia. Among 75 patients with chronic insomnia, both groups improved significantly, and there was no statistical difference in effectiveness between them. Valerian had fewer side effects, with only two withdrawals compared to three in the oxazepam group. The researchers concluded valerian had a “more favourable adverse effect profile” while delivering comparable results.
How Long Before It Works
This depends entirely on how you’re using it. For acute situational anxiety, like pre-surgery nerves, a single dose taken about 60 minutes beforehand can help. For stress reduction under challenging conditions, one week of daily use at 600 mg showed results. But for broader, ongoing anxiety, most positive trials ran for four weeks before measuring significant improvement.
If you’re expecting overnight results for generalized anxiety, valerian will likely disappoint. The evidence suggests it works more like an antidepressant than a fast-acting sedative: consistent daily use over weeks builds the effect. For one-time stressful events, it can work much faster, but at that point you’re getting mild sedation rather than true anxiolytic benefit.
Dosage for Anxiety
The European Medicines Agency recommends 400 to 600 mg of dry hydroalcoholic extract for nervous tension, or 0.3 to 3 grams of the raw root substance up to three times daily. Clinical trials for anxiety have used doses ranging widely, from 100 mg for acute situations to 1,260 mg for premenstrual symptoms.
A reasonable starting point for general anxiety is 300 to 600 mg per day of a standardized extract. Look for products standardized to at least 0.8% valerenic acid, which is the concentration used in clinical trials. The European pharmacopoeia sets the minimum valerenic acid content at 0.25% for alcohol-based extracts and just 0.02% for water-based extracts, so products vary enormously. A supplement that simply says “valerian root” without specifying valerenic acid content may contain very little of the active compound.
Side Effects and Safety
Valerian is generally well tolerated. The most common side effects are mild: headache, stomach upset, mental dullness, and occasionally vivid dreams. Some people experience a paradoxical reaction of excitability or uneasiness rather than calm.
Liver injury has been reported but is extremely rare. A review by the National Institutes of Health classified valerian as a “probable rare cause” of liver injury. Among 85 cases of supplement-related liver problems tracked in one U.S. study over nearly a decade, only one was attributed to valerian. The handful of documented cases mostly involved combination products containing other herbs like skullcap or black cohosh, making it hard to pin the damage on valerian alone. In isolated cases where valerian was the sole supplement, liver enzymes typically returned to normal within 4 to 10 weeks of stopping.
The safety of long-term use has not been well studied. If you’ve been taking valerian daily for an extended period, don’t stop abruptly. Withdrawal symptoms including rebound anxiety, irritability, insomnia, heart disturbances, and in rare cases hallucinations have been reported after sudden discontinuation of chronic use. Tapering off gradually is the safer approach.
Interactions With Other Substances
Because valerian works on the same brain receptors as sedative medications, combining it with other calming substances can amplify sedation to potentially dangerous levels. Valerian increases the effects of benzodiazepines, narcotic pain medications, other sleep aids, and alcohol. If you’re taking any prescription sedative or anti-anxiety medication, adding valerian on top creates a risk of excessive drowsiness, slowed breathing, or impaired coordination.
The Bottom Line on Effectiveness
Valerian root has a plausible mechanism, real clinical data behind it, and a favorable safety profile compared to prescription alternatives. It’s a reasonable option for mild anxiety, situational stress, or as a sleep aid when anxiety is disrupting rest. Where it falls short is in the quality and size of the evidence: most trials are small, and the dosages and preparations vary so much that it’s hard to give a single confident recommendation. For moderate to severe anxiety disorders, valerian alone is unlikely to be sufficient. For the kind of everyday tension and stress that drives most people to search for natural remedies, the evidence suggests it can genuinely help, particularly at doses of 300 to 600 mg daily over several weeks.