Valerian root

Valerian Root (Valeriana officinalis)

1. Identity: Botanical Classification, Natural Source, and Common Names

Valeriana officinalis is the most typically used species of the plant genus Valeriana in herbal medicine. Valeriana officinalis Linn. is a perennial herbaceous plant belonging to the family Valerianaceae, widely distributed in temperate regions; the genus comprises approximately 250 species, of which 11 out of 28 Chinese varieties are used as herbal medicines.

The name valerian derives from the Latin word valere, which means "to be in good health." Common synonyms and trade names include garden heliotrope, mountain heliotrope, and all-heal. Related species used medicinally in other traditions include Valeriana jatamansi (Indian valerian, known in Ayurvedic medicine as Tagara), Valeriana edulis (Mexican valerian), and several East Asian species.

The roots and rhizomes (underground stems) of valerian are the parts used for medicinal purposes. Valeriana spp. is listed in the European and USA pharmacopeias and is one of the highest-selling natural medicines in Europe and the USA.

Dried roots are prepared as teas or tinctures, and dried plant materials and extracts are put into capsules or incorporated into tablets. In medicinal and commercial use, the relevant plant material is typically the root and rhizome, which may be sold as tea-cut herb, milled powder, tincture, tablet, capsule ingredient, or spray-dried extract powder.

2. Traditional and Historical Use

Ancient Greece and Rome

Valerian has been used as a medicinal herb since at least the time of ancient Greece and Rome. Historically, valerian was used to treat insomnia, migraine, fatigue, and stomach cramps. Hippocrates described its properties, and Galen later prescribed it as a remedy for insomnia. Valerian has been used for centuries in Europe, usually for digestive and urinary problems.

Classical Herbalists and the Middle Ages

The historical medicinal usage of valerian by herbalists includes Pliny (23 CE–79 CE), who recommended it for pain relief; Dioscorides, who used it as a diuretic; Galen, who prescribed it as a decongestant; Hildegard of Bingen (1098–1179), who recommended it for its tranquilizing effects and as a sleep aid; John Gerard (1545–1611), who promoted it as a treatment for chest congestion, convulsions, and bruises; and Culpeper (1616–1654), who thought it was useful against the plague, as well as for coughs and wounds. The Eclectics (19th century) touted it as a calmative and treatment for epilepsy.

In medieval Sweden, it was sometimes placed in the wedding clothes of a bridegroom to ward off the "envy" of the elves. During both World Wars, valerian was used as a nervine to treat shell shock and was included in tablets to help calm citizens living under the threat of nightly bombings.

Traditional Preparations

The form under which the ancients knew valerian was not the entire plant fresh, but only the root in dried form. Traditional preparations included infusions of 1–2 grams of dried root daily. By the 19th century, industrial methods expanded the pharmacopoeial repertoire: industrial-scale distilleries refined alcohol extraction, and fluid extracts, ammoniated tinctures, and concentrated "compound drops" appeared in medical compendia on both sides of the Atlantic.

Other Cultural Traditions

In traditional herbal medicine, valerian root was used for centuries across various cultures, including ancient Greek, Roman, and Chinese medical practices, to treat a wide range of conditions from sleep disorders to anxiety and nervous system imbalances. In Ayurvedic medicine, Valeriana wallichii (Tagara) was traditionally used for anxiety, calmness, and sleep.

The Greeks used valerian to ward off evil, hanging valerian bunches in windows, while the Celts hung it in their homes to ward off lightning. Salves containing valerian have been applied in the treatment of rashes, sore muscles, and bruising.

3. Key Constituents and Active Compounds

There is no scientific agreement as to the active constituents of valerian, and its activity may result from interactions among multiple constituents rather than any one compound or class of compounds. The content of volatile oils, including valerenic acids; the less volatile sesquiterpenes; or the valepotriates (esters of short-chain fatty acids) is sometimes used to standardize valerian extracts. As with most herbal preparations, many other compounds are also present.

Primary Compound Classes

• Sesquiterpenic acids: Valerenic acid is a main constituent of Valeriana officinalis, most widely used in Europe and the USA. Related derivatives include acetoxyvalerenic acid and hydroxyvalerenic acid. The European Pharmacopoeia mandates a minimum of 0.17% sesquiterpenic acids (expressed as valerenic acid) in cut root material, alongside at least 0.5 mL/kg essential oil content.
• Valepotriates (iridoid esters): The identified constituents include iridoids known as valepotriates (valtrate, isovaltrate, didrovaltrate, and acevaltrate). Valepotriates constitute 0.1–2% of the dry root weight. These iridoid esters are unstable and degrade rapidly during storage, aqueous extraction, or exposure to heat, light, or acidic conditions, with losses of up to 50% within months; their breakdown product, baldrinal, is a cytotoxic aldehyde.
• Essential oils: Approximately 0.5%–2.0% of Valeriana spp. consists of essential oils by GC-MS analysis, which varies with species, climate, and growing environment. These include monoterpenes (e.g., borneol, bornyl acetate), sesquiterpenes (e.g., valerenal, valerenic acid), and carboxylic compounds (valeric/isovaleric acid).
• Flavonoids and lignans: Several constituents of Valeriana officinalis have been found to have sedative or anxiolytic properties, including valerenic acid (VA), 6-methylapigenin (MA), (2S)-hesperidin (HN), and the flavonoid glycoside linarin (LN). VA and MA have been shown to have GABAergic activity, while the mechanism by which LN and HN produce sedative effects is still unknown but does not appear to be via GABAergic pathways.
• Free amino acids: The roots and rhizomes are rich in essential oils, iridoids, flavonoids, alkaloids, amino acids, and lignanoids. Notably, low levels of GABA itself have been detected directly in the plant material.
• Pentanoic acid (valeric acid): Valerian extract comprises at least two compounds significantly involved in post-synaptic GABAergic reactions: valerenic acid (VA), which acts as an allosteric modulator of the GABA_A receptor, and pentanoic acid (PA), which inhibits GABA transaminase (GABA-T) activity, prolonging the action of GABA on its receptor.

Constituent Variability by Preparation

When a herbal tea is prepared by hot extraction from valerian root, up to 60% of the valepotriates remain in the root material and only 0.1% can be recovered from the tea. A freshly prepared tincture contains 11% of the valepotriates originally found in the root material, rapidly reducing to 3.7% after 1 week and 0% after 3 weeks at room temperature.

4. Mechanisms of Action

GABAergic Modulation

A possible mechanism by which a valerian extract may cause sedation is by increasing the amount of gamma aminobutyric acid (GABA, an inhibitory neurotransmitter) available in the synaptic cleft. Valerenic acid and valerenol have a specific binding site on GABA_A receptors with nanomolar affinity, and both agents enhanced the response to GABA at multiple types of recombinant GABA_A receptors.

A point mutation in the β2 or β3 subunit (N265M) of recombinant receptors strongly reduced the drug response. In vivo, valerenic acid and valerenol exerted anxiolytic activity with high potencies in animal behavioral tests; in β3 (N265M) point-mutated mice, the anxiolytic activity of valerenic acid was absent, indicating that neurons expressing β3-containing GABA_A receptors are a major cellular substrate for the anxiolytic action of valerian extracts. This work was published in Neuropharmacology (2008) and is the strongest pharmacological evidence to date for valerenic acid's mechanism.

Valerian extracts also show a significant affinity for the serotonin receptor (5-HT_5a), which is well known to modulate sleep-wake cycles and circadian rhythms in the human brain via a G-protein-coupled receptor family.

Activation of adenosine receptors has also been implicated in the action of valerian ingredients.

Despite these mechanistic insights, these compounds are reported for interfering with the brain receptor for the neurotransmitter GABA, but the detailed mechanism of action as a mild sedative is still considered unknown. The overall biological activity of valerian extract is not yet fully understood and is likely to reflect synergistic actions across multiple compound classes.

5. Scientific Evidence by Area of Use

5.1 Sleep Disorders and Insomnia

Valerian (Valeriana officinalis L.) is a popular herbal medicine used as a sleep aid; however, the outcomes of previous clinical studies are inconsistent.

2020 Systematic Review and Meta-Analysis (Shinjyo, Waddell, Green — PMC): PubMed, ScienceDirect, and the Cochrane Library were searched for publications relevant to the effectiveness of valerian as a treatment for sleep problems and associated disorders. A total of 60 studies (n=6,894) were included in this review, and meta-analyses were performed to evaluate the effectiveness to improve subjective sleep quality (10 studies, n=1,065) and to reduce anxiety (8 studies, n=535).

2006 Systematic Review and Meta-Analysis (Bent et al. — PMC): A systematic review of randomized, placebo-controlled trials of valerian for improving sleep quality identified 16 eligible studies examining a total of 1,093 patients. Most studies had significant methodologic problems, and the valerian doses, preparations, and length of treatment varied considerably.

In another systematic review of the scientific literature, nine randomized, placebo-controlled, double-blind clinical trials of valerian and sleep disorders were identified and evaluated for evidence of efficacy. Reviewers rated the studies using a standard scoring system; although all nine trials had flaws, three earned the highest rating (5 on a scale of 1 to 5).

A frequently cited study by Leathwood and Chauffard (1985) used objective wrist-worn activity meters: Eight volunteers with mild insomnia received 450 mg or 900 mg of aqueous valerian extract and placebo; the 450 mg dose reduced average sleep latency from about 16 to 9 minutes, similar to the effect of benzodiazepine medication.

Overall evidence strength: There is not enough evidence to determine whether valerian is useful for any health conditions. The evidence on whether valerian is helpful for sleep problems is inconsistent. NIH ODS describes the evidence for sleep disorders as inconclusive, and NCCIH states that current research does not clearly establish that valerian helps with sleep problems. The body of literature is limited by heterogeneity in extract type, dose, preparation, duration, outcome measures, and study quality.

5.2 Anxiety

In the 2020 systematic review, valerian root/rhizome 530 mg per day for 4 weeks reduced anxiety in HIV-positive patients receiving efavirenz, suggesting valerian could prevent neuropsychiatric adverse effects caused by the antiretroviral medication. Valerian extract 100 mg, as a single dose 60 minutes before the initiation of surgical operation, reduced anxiety in patients undergoing dental operations.

Valerian extract 1,260 mg per day for 7 days for 3 menstrual cycles effectively reduced premenstrual anxiety in one RCT (Jadad scale 5). However, an internet-based study with volunteers with non-clinical anxiety and insomnia found no significant difference in State-Trait Anxiety Inventory (STAI) compared to placebo.

A 2006 meta-analysis concluded that there was insufficient evidence to determine valerian's effectiveness or safety for anxiety disorders. There is not enough evidence to allow any conclusions about whether valerian is helpful for anxiety, depression, premenstrual syndrome, dysmenorrhea, stress, or other conditions.

5.3 Menopause Symptoms (Vasomotor)

Three small studies suggest that valerian might be helpful for menopause symptoms, but there is not enough evidence to know for certain.

One randomized, double-blind clinical trial enrolled 68 menopausal women with the chief complaint of hot flash, randomly divided into drug and placebo groups; women in the drug group were prescribed 255 mg valerian capsules three times a day for 8 weeks. The severity of hot flashes revealed a meaningful statistical difference pre- and post-valerian treatment (p<0.001), while this difference was not meaningful in the placebo group; valerian also led to a reduction of hot flash frequencies 4 and 8 weeks after treatment (p<0.001).

All published menopause-related studies are inconsistent as they involve heterogeneous groups of women. Therefore, it is uncertain whether valerian preparations are really effective in alleviating central nervous system disorders in menopause.

5.4 Restless Legs Syndrome (RLS)

One RCT (Cuellar and Ratcliffe, 2009) examined this indication: the objective was to compare the effects of 800 mg of valerian with a placebo on sleep quality and symptom severity in people with RLS; 37 participants were randomly assigned to receive 800 mg of valerian or placebo for 8 weeks, with primary outcomes including sleep quality and RLS symptom severity. The results suggest that the use of 800 mg of valerian for 8 weeks improves symptoms of RLS and decreases daytime sleepiness in patients that report an Epworth Sleepiness Scale score of 10 or greater. However, this was a very small trial (n=37), and there is no good evidence overall that valerian decreases the severity of RLS symptoms; the American Academy of Sleep Medicine 2024 guidelines explicitly recommend against the use of valerian for RLS due to lack of evidence.

5.5 Premenstrual Syndrome and Dysmenorrhea

In a double-blind, placebo-controlled clinical trial, the effect of valerian root extract supplements was assessed on premenstrual syndrome; valerian root extract supplementation (530 mg, twice daily) significantly improved the emotional and physical symptoms associated with PMS compared to placebo. This represents preliminary positive data, but the overall evidence base for PMS and dysmenorrhea remains insufficient to draw firm conclusions.

5.6 Other Investigated Areas

Valerian may potentially be beneficial for postoperative cognitive impairment and attention-deficit/hyperactivity disorder (with lemon balm). In vitro, valerian shows antioxidant, cytoprotective, and neuroprotective effects. In animal research, valerian has shown antihypertensive, anxiolytic, antidepressant, and antispasmodic effects. These effects have not been robustly confirmed in human clinical trials and must be considered preliminary or preclinical.

6. Dosage Forms and Reported Dosages

Dried roots are prepared as teas or tinctures, and dried plant materials and extracts are put into capsules or incorporated into tablets.

Preparations and Dose Ranges Used in Clinical Studies

• Capsules/tablets (standardized extract): Research suggests that valerian is generally safe for short-term use by most adults, and has been used with apparent safety in doses of 300 to 600 milligrams daily for up to 6 weeks. Taking valerian root extract 300–600 mg by mouth daily appears to improve sleep quality; it may take up to 4 weeks of use to notice an effect.
• Higher single doses: In one study, 450 mg or 900 mg of aqueous valerian extract was used; the 450 mg dose reduced average sleep latency from about 16 to 9 minutes. At 900 mg, increased next-morning sleepiness has been reported.
• RLS dosing: The comparison dose in the RLS trial was 800 mg daily (37 participants) for 8 weeks.
• Anxiety dosing: In some trials, a 100 mg single dose was used pre-operatively for anxiety reduction. In premenstrual anxiety, 1,260 mg per day for 7 days per cycle was used.
• Menopause dosing: In the hot flash trial, 255 mg three times a day (765 mg/day total) was used for 8 weeks.
• Herbal tea: Tea uses the dried root itself; the standard preparation is 2 to 3 grams of dried root steeped in one cup of hot water for 10 to 15 minutes, then strained.
• Standardization markers: Good-quality valerian root powders contain at least 0.1% valerenic acids, while powdered extracts are typically standardized to 0.4–0.8% valerenic acids. Many clinical trials have used LI 156 (Sedonium), a standardized commercial preparation of dried valerian root extract; many extracts are standardized to 0.8% valerenic acids, with common potencies delivering 450 mg of total extract per dose.

The dose and duration of use of valerian varied widely between studies, making it difficult to form conclusions related to the effectiveness of valerian.

7. Safety Considerations and Interactions

General Safety Profile

Valerian is generally considered fairly safe with few adverse effects reported. Daytime sedation and gastrointestinal disturbances have been reported to occur after use of valerian. The safety of long-term use of valerian is unknown. Side effects of valerian include headache, stomach upset, mental dullness, excitability, uneasiness, and vivid dreams.

Withdrawal Symptoms

Some individuals may experience withdrawal symptoms, including anxiety, irritability, heart disturbances, insomnia, and in rare cases, hallucinations, if valerian is stopped abruptly after chronic use. There have been a few reports of withdrawal symptoms in people who stopped taking valerian abruptly after long-term use.

Hepatotoxicity

Valerian has been implicated in a small number of cases of clinically apparent liver injury, but usually in combination with other botanicals such as skullcap or black cohosh. In view of its wide-scale use, valerian has to be considered a very rare cause of hepatic injury. In published cases, the latency to onset ranged from 3 to 12 weeks and the pattern of enzyme elevations was usually hepatocellular or mixed hepatocellular-cholestatic. The National Institutes of Health rates valerian as a "probable rare cause" of liver injury, noting that no convincing cases of serious liver failure have been attributed to valerian alone. There have been cases reported in the literature suggesting Valeriana officinalis can cause liver injury; based on the evidence to date, it appears that liver injury associated with Valeriana officinalis is very rare.

Drug Interactions

In vitro studies have suggested that valerian inhibits both CYP3A4 metabolism and p-glycoprotein activity, but no clinical studies have shown any drug metabolism interactions. Valerian may prolong the effect of other sedatives (e.g., barbiturates) and affect driving or other activities requiring alertness, and should not be taken along with alcohol or sedatives.

A systematic review identified seven in vitro studies on six CYP450 isoenzymes, p-glycoprotein, and two UGT isoenzymes; the methodological assessment of these studies did not support their suitability for the prediction of clinically relevant interactions. Clinical studies on various valerian preparations did not reveal any relevant interaction potential concerning CYP 1A2, 2D6, 2E1, and 3A4. Available animal and human pharmacodynamic studies did not verify any interaction potential, and the interaction potential of valerian preparations therefore seems to be low and without clinical relevance.

Special Populations

Those who are pregnant or nursing and children under the age of 3 should not take valerian root, as the risks have not been adequately studied in these groups. Studies of the longer-term safety of valerian root supplementation have not been conducted.

Regulatory Status

Valerian root is considered a dietary supplement in the United States, so it is not regulated by the FDA; there is no official dosage recommendation and no mandatory oversight on supplement composition. According to the chemical information review document published by the National Toxicology Program (NIH, 2009), V. officinalis has no carcinogenicity, cogenotoxicity, nor immunotoxicity.

Constituent Quality and Stability Concerns

Valepotriates constitute 0.1–2% of the dry root weight and are unstable, degrading rapidly during storage, aqueous extraction, or exposure to heat, light, or acidic conditions, with losses of up to 50% within months; their breakdown product, baldrinal, is a cytotoxic aldehyde. Several valerian-containing products sold in pharmacies have been evaluated to verify the presence of Valeriana officinalis; the content of valerenic acid was found to vary considerably in the products analyzed, thus emphasizing the importance of standardizing herbal preparations.

References

• NIH Office of Dietary Supplements — Valerian: Health Professional Fact Sheet
• NCCIH — Valerian: Usefulness and Safety
• NIH LiverTox® — Valerian (NCBI Bookshelf)
• Shinjyo N, Waddell G, Green J. "Valerian Root in Treating Sleep Problems and Associated Disorders — A Systematic Review and Meta-Analysis." Journal of Evidence-Based Integrative Medicine, 2020 (PMC7585905)
• Bent S, et al. "Valerian for Sleep: A Systematic Review and Meta-Analysis." The American Journal of Medicine, 2006 (PMC4394901)
• Benke D, et al. "GABA_A receptors as in vivo substrate for the anxiolytic action of valerenic acid." Neuropharmacology, 2009 (PubMed 18602406)
• Chen HW, et al. "Chemical Components and Cardiovascular Activities of Valeriana spp." Evidence-Based Complementary and Alternative Medicine, 2015 (PMC4695638)
• Mirabi P, Mojab F. "The Effects of Valerian Root on Hot Flashes in Menopausal Women." Iranian Journal of Pharmaceutical Research, 2013 (PMC3813196)
• Cuellar NG, Ratcliffe SJ. "Does valerian improve sleepiness and symptom severity in people with restless legs syndrome?" Alternative Therapies in Health and Medicine, 2009 (PubMed 19284179)
• Kelber O, Nieber K, Kraft K. "Valerian: No Evidence for Clinically Relevant Interactions." Evidence-Based Complementary and Alternative Medicine, 2014
• Yeung KS, et al. "Medicinal Plants Used for Anxiety, Depression, or Stress Treatment: An Update." Pharmaceuticals, 2022 (PMC9500625)
• American Botanical Council HerbalGram — "Valerian: Historical, Mythical, and Magical Uses"
• Therapeutic Goods Administration (TGA, Australia) — Valerian Safety Alert
• Merck Manual Professional Edition — Valerian