More than 200 plant species belong to the genus Valeriana, but the one most commonly used as an herb is Valeriana officinalis. The root is used for medicinal purposes.
Galen recommended valerian for insomnia in the second century AD. From the sixteenth century onward, this herb became popular as a sedative in Europe (and later, the United States). Scientific studies on valerian in humans began in the 1970s, leading to its approval as a sleep aid by Germany's Commission E in 1985. However, the scientific evidence showing that valerian really works remains incomplete.
As with most herbs, we are not exactly sure which ingredients in valerian are most important.1,2 Early research focused on a group of chemicals known as valepotriates, but they are no longer considered candidates. A constituent called valerenic acid has also undergone study, but its role is far from clear. Another substance in valerian, called linarin, has also attracted research interest.51
Our understanding of how valerian might function remains similarly incomplete. Several studies suggest that valerian affects GABA, a naturally occurring amino acid that appears to be related to the experience of anxiety.3-6 Conventional tranquilizers in the Valium family are known to bind to GABA receptors in the brain, and valerian may work similarly. However, there are some significant flaws in these hypotheses, and the reality is that we don't really know how valerian works (or if, indeed, it really does).7,8
Valerian is commonly recommended as a mild treatment for occasional insomnia. However, evidence from the best positive study on valerian suggests that it is only useful when taken over an extended period of time for chronic sleep disorders.9 Overall, it is not clear whether valerian is effective for sleep at all.64
Like other treatments used for insomnia, valerian has also been proposed as a treatment for anxiety, but there is no reliable evidence as yet that it is effective.
Finally, valerian is sometimes suggested as a treatment for a nervous stomach; however, as of yet, there is no supporting scientific evidence for this use.
Overall, the evidence supporting valerian as a sleep aid remains substantially incomplete and contradictory.61 A systematic review published in 2007 concluded that valerian is probably not effective for treating insomnia.64 And in a subsequent review of 18 randomized trials, researchers found that people who took valerian did report an improvement in their sleep, but this finding was not supported by more objective measures of sleep quality.67
However, there have been some positive results, both with valerian alone and valerian combined with other herbs.
The best positive study of valerian for insomnia followed 121 people for 28 days.10 In this double-blind, placebo-controlled trial, half of the participants took 600 mg of an alcohol-based valerian extract 1 hour before bedtime, while the other half took placebo. Valerian didn't work right away. For the first couple of weeks, valerian and placebo were running neck and neck. However, by day 28, valerian pulled far ahead. Effectiveness was rated as good or very good by participant evaluation in 66% of the valerian group and in 61% by doctor evaluation, whereas in the placebo group, only 29% were so rated by participants and doctors.
Although positive, these results are a bit confusing. In another large study, valerian was immediately more effective than placebo, which is more in keeping with how the herb is typically used. This trial followed 128 subjects who had no sleeping problems.11 On nine nonconsecutive nights, each participant took one of three treatments: valerian, a combination of valerian and the herb hops, or placebo. The results showed that on the nights they took valerian alone, participants fell asleep faster than when they were taking placebo, or the combination. In contradiction to this, other studies have failed to find any immediate mental depressant effects with valerian; most substances that rapidly induce sleep also sedate the mind.45,46
Furthermore, the more recent and best designed studies have generally failed to find valerian more helpful at all.47,54,64,66 One of these was a 4-week study in which 135 people were given valerian and 135 given placebo.56 Another was a two-week study of 405 people which found “modest benefits at most [italics added].” 65
A 6-week, double-blind study of 202 people with insomnia compared valerian extract (600 mg at bedtime) with the standard drug oxazepam (10 mg at bedtime) and found equal efficacy.53 Equivalent benefits were also seen in similar study of 75 people.13 However, the absence of a placebo group in these two studies decreases the reliability of the results.
A study of 184 people tested a standardized combination of valerian and hops, with mixed results.63 Researchers tested quite a few aspects of sleep (such as time to fall asleep, length of sleep, number of awakenings) and found evidence of benefit in only a few. This use of “multiple outcome measures” makes the results somewhat unreliable.
A much smaller study also found evidence that a combination of hops and valerian extract is more effective as a sleep aid than placebo; the results of this trial also hint that hops plus valerian is more effective than valerian alone, but this possible finding did not reach statistical significance.62
A double-blind comparative study that enrolled 46 patients compared the effects of the standard drug bromazepam to a mixture of valerian and hops with either treatment taken one-half hour before bed.14 The results suggest that the two treatments were equally effective. One study found that this valerian-hops combination can antagonize the arousal produced by caffeine.48
A combination of valerian and lemon balm has also been tried for insomnia. A rather poorly designed 30-day, double-blind, placebo-controlled study of 98 individuals without insomnia found marginal evidence that a valerian-lemon balm combination improved sleep quality as compared to placebo.15 However, a double-blind crossover study of 20 people with insomnia compared the benefits of the sleeping drug Halcion (0.125 mg) against placebo and a combination of valerian and lemon balm, and failed to find the herb effective.16 The drug, however, did prove effective.
Valerian has shown some promise for helping people sleep better after discontinuing conventional sleeping pills in the benzodiazepine family.43
In a double-blind, placebo-controlled study, 36 people with generalized anxiety disorder were given either valerian extract, Valium, or placebo for a period of 4 weeks.44 The study failed to find statistically significant differences between the groups, presumably due to its small size.
Valerian has also been tested for possible benefits during stressful circumstances. Two preliminary double-blind studies found weak evidence that valerian may produce calming effects in induced stressful situations.17,58 Another study evaluated the effects of a combination containing valerian and lemon balm taken in various doses.59 Some benefits were seen with doses of 600 mg or 1200 mg three times daily, but the highest dose (1,800 mg 3x daily) actually appeared to increase anxiety symptoms during a stressful situation. Furthermore, people taking the herbal treatment at any dose showed slightly decreased cognitive function as compared to those given placebo.
For insomnia, the standard adult dosage of valerian is 2 g to 3 g of dried herb, 270 mg to 450 mg of an aqueous valerian extract, or 600 mg of an ethanol extract, taken 30 to 60 minutes before bedtime.23 The same amount, or a reduced dose, can be taken twice daily for anxiety.
Because of valerian's unpleasant odor, European manufacturers have created odorless valerian products. However, these are not yet widely available in the United States.
Valerian is not recommended for children under 3 years old.24
Valerian is on the FDA's GRAS (generally recognized as safe) list and is approved for use as a food. In animals, it takes enormous doses of valerian to produce any serious adverse effects.25 Valerian has shown an excellent safety profile in clinical trials.64
In a suicide attempt, one young woman took approximately 20 g of valerian (20 to 40 times the recommended dose). Only mild symptoms developed, including stomach cramps, fatigue, chest tightness, tremors, and light-headedness. All of these resolved within 24 hours, after two treatments with activated charcoal.26 The woman's lab tests—including tests of her liver function—remained normal. Keep in mind that this does not mean that you can safely exceed the recommended dose!
One report did find toxic results from herbal remedies containing valerian mixed with several other herbal ingredients, including skullcap. Four individuals who took these remedies later developed liver problems.27 However, skullcap products are sometimes contaminated with the liver-toxic herb germander, and this could have been the explanation.
There have also been about 50 reported cases of overdose with a combination preparation called Sleep-Qik, which contains valerian as well as conventional medications.28,29 Researchers specifically looked for liver injury, but found no evidence that it occurred.
There are some safety concerns about valepotriates, constituents of valerian, because in test tube studies they have been found to affect DNA and cause other toxic effects. However, valepotriates are not present to a significant extent in any commercial preparations.30,31
Although no animal studies or controlled human trials have found evidence that valerian causes withdrawal symptoms when stopped, one case report is sometimes cited in support of the possibility that this might occur.32 It concerns a 58-year-old man who developed delirium and rapid heartbeat after surgery. According to the patient's family, he had been taking high doses of valerian root extract (about 2.5 g to 10 g per day) for many years. His physicians decided that he was suffering from valerian withdrawal. However, considering the many other factors involved (such as multiple medications and general anesthesia), it isn't really possible to conclude that valerian caused his symptoms.
In clinical trials, use of valerian has not been associated with any significant side effects. A few people experience mild gastrointestinal distress, and there have been rare reports of people developing a paradoxical mild stimulant effect from valerian.
Valerian does not appear to impair driving ability or produce morning drowsiness when taken at night.35-38 As noted above, most studies have failed to find any immediate sedative effect with valerian. However, one study reported finding mild impairment of attention for a couple of hours after taking valerian.49 For this reason, it isn't a good idea to drive immediately after taking it.
There have been no reported drug interactions with valerian, and two studies found reasons to believe that valerian should not raise or lower the blood levels of too many medications.55,60 Nonetheless, there are at least theoretical concerns that valerian might amplify the effects of sedative drugs. A 1995 study was somewhat reassuring on this score because it found no interaction between alcohol and valerian.40 However, animal studies have found that valerian extracts may prolong the effects of some sedatives,41,42 and there have been some worrisome case reports suggesting that the combination of valerian and alcohol can lead to excessive sedation in some people.50 For this reason, we recommend that you do not combine valerian with central nervous system depressants except under doctor’s supervision.
Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.
If you are taking sedative drugs such as benzodiazepines; don't take valerian in addition to them, except under physician supervision.
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3. Santos MS, Ferreira F, Cunha AP, et al. Synaptosomal GABA release as influenced by valerian root extract—involvement of the GABA carrier. Arch Int Pharmacodyn Ther. 1994;327:220-231.
4. Santos MS, Ferreira F, Cunha AP, et al. An aqueous extract of valerian influences the transport of GABA in synaptosomes. Planta Med. 1994;60:278-279.
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6. Mennini T, Bernasconi P, Bombardelli E, et al. In vitro study on the interaction of extracts and pure compounds from Valeriana officinalis roots with GABA, benzodiazepine, and barbiturate receptors in rat brain. Fitoterapia. 1993;64:291-300.
7. Santos MS, Ferreira F, Faro C, et al. The amount of GABA present in aqueous extracts of valerian is sufficient to account for [ 3H ] GABA release in synaptosomes. Planta Med. 1994;60:475-476.
8. Cavadas C, Arajo I, Cotrim MD, et al. In vitro study on the interaction of Valeriana officinalis L. extracts and their amino acids on GABAa receptor in rat brain. Arzneimittelforschung. 1995;45:753-755.
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44. Andreatini R, Sartori VA, Seabra ML, et al. Effect of valepotriates (valerian extract) in generalized anxiety disorder: a randomized placebo-controlled pilot study. Phytother Res. 2002;16:650-654.
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49. Gerhard U, Linnenbrink N, Georghiadou C, et al. Vigilance-decreasing effects of 2 plant-derived sedatives. Schweiz Rundsch Med Prax. 1996;85:473-481.
50. Chen D, Klesmer J, Giovanniello A, et al. Mental status changes in an alcohol abuser taking valerian and gingko biloba. Am J Addict. 2002;11:75-77.
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Last reviewed December 2015 by EBSCO CAM Review Board
Last Updated: 12/15/2015