Valerian

Valerian is the herb’s flagship indication and the most trial-rich. Early positive work includes a 128-person crossover study of a 400 mg aqueous extract that reduced subjectively rated sleep latency, most in self-described poor sleepers ^{8Reference 8Leathwood PD et al. · 1982Aqueous extract of valerian root improves sleep quality in manView study →}. Meta-analyses split along the subjective/objective divide: Bent (2006) pooled 16 trials (n=1,093) and found a significant benefit on dichotomous sleep quality (RR 1.8, 95% CI 1.2–2.9) but flagged publication bias ^{2Reference 2Bent S et al. · 2006Meta-analysisValerian for sleep: a systematic review and meta-analysisView study →}; Fernández-San-Martín (2010) pooled 18 RCTs and found improved sleep quality (RR 1.37) yet no difference in objectively timed sleep latency (mean difference 0.70 min) ^{3Reference 3Fernández-San-Martín MI et al. · 2010Meta-analysisEffectiveness of Valerian on insomnia: a meta-analysis of randomized placebo-controlled trialsView study →}; Shinjyo (2020) pooled 60 studies and concluded valerian is safe and effective for subjective quality, attributing inconsistency to variable extract quality and favouring whole root/rhizome ^{1Reference 1Shinjyo N et al. · 2020Meta-analysisValerian Root in Treating Sleep Problems and Associated Disorders — A Systematic Review and Meta-AnalysisView study →}. Against these, the most rigorous reviews are negative — Taibi (2007), “safe but not effective,” found the newest and best-designed trials showed no effect ^{4Reference 4Taibi DM et al. · 2007Systematic reviewA systematic review of valerian as a sleep aid: safe but not effectiveView study →}; a controlled trial in older women with insomnia found no improvement on self-report, PSG, or actigraphy, with wake-after-sleep-onset (time awake after first falling asleep) even increasing significantly on valerian ^{11Reference 11Taibi DM et al. · 2009RCTA randomized clinical trial of valerian fails to improve self-reported, polysomnographic, and actigraphic sleep in older women with insomniaView study →}; a phase III trial in 227 cancer patients (450 mg) missed its primary PSQI endpoint ^{12Reference 12Barton DL et al. · 2011RCTThe use of Valeriana officinalis in improving sleep in patients undergoing cancer treatment: a phase III RCT (NCCTG N01C5)View study →}; and a 2024 umbrella review concluded valerian lacks empirical support for insomnia despite good safety ^{6Reference 6Valente V et al. · 2024ReviewDoes valerian work for insomnia? An umbrella review of the evidenceView study →}. Some positive signals persist in specific populations — postmenopausal women (530 mg twice daily) ^{9Reference 9Taavoni S et al. · 2011RCTEffect of valerian on sleep quality in postmenopausal women: a randomized placebo-controlled clinical trialView study →}, post-CABG surgical patients (530 mg) ^{10Reference 10Zare Elmi H et al. · 2021RCTEfficacy of Valerian Extract on Sleep Quality after Coronary Artery Bypass Graft Surgery: A Triple-Blind Randomized Controlled TrialView study →}, an 8-week trial of a standardised extract improving PSQI ^{7Reference 7Chandra Shekhar H et al. · 2024RCTStandardized Extract of Valeriana officinalis Improves Overall Sleep Quality: A Randomized, Double-Blind, Placebo-Controlled Clinical StudyView study →} — and valerian-hops combinations modestly increase sleep duration ^{13,14Reference 13Morin CM et al. · 2005RCTValerian-hops combination and diphenhydramine for treating insomnia: a randomized placebo-controlled clinical trialView study →Reference 14Schicktanz N et al. · 2025RCTEffects of a Valerian-Hops Extract Combination (Ze 91019) on Sleep Duration and Daytime Parameters in Occasional Insomnia: A Randomized Controlled Feasibility TrialView study →}.

Gap: the benefit is confined to subjective self-report; objective sleep architecture is essentially unchanged, and heterogeneity of extract type and dose prevents a clear effective-dose recommendation.

Valerian’s anxiolytic reputation rests on an unusually well-mapped mechanism. valerenic acid and its alcohol valerenol bind a specific site on GABA-A receptors with nanomolar affinity and enhance GABA responses, an effect dependent on the receptor β2/β3 subunit ^{23,24Reference 23Khom S et al. · 2007Valerenic acid potentiates and inhibits GABA(A) receptors: molecular mechanism and subunit specificityView study →Reference 24Benke D et al. · 2009AnimalGABA-A receptors as in vivo substrate for the anxiolytic action of valerenic acidView study →}. The causal link to behaviour is strong: valerenic acid and valerenol are anxiolytic in the elevated-plus-maze and light/dark tests in wild-type mice, but the effect is abolished in β3(N265M) point-mutant mice — direct in-vivo evidence that β3-containing GABA-A receptors mediate the action ^{24Reference 24Benke D et al. · 2009AnimalGABA-A receptors as in vivo substrate for the anxiolytic action of valerenic acidView study →}. A companion study showed the anxiolytic effect tracks valerenic acid specifically and is cancelled by co-occurring acetoxyvalerenic acid, which helps explain preparation-dependent inconsistency ^{25Reference 25Becker A et al. · 2014The anxiolytic effects of a Valerian extract is based on valerenic acidView study →}. More recent mouse work reproduces a diazepam-comparable anxiolytic effect at 12 mg/kg without sedation or locomotor change ^{30Reference 30Pinder NE et al. · 2024AnimalValerenic acid reduces anxiety-like behavior in young adult, female (C57BL/6J) miceView study →}, and valerenic acid lowers stress corticosterone and monoamine turnover in the hippocampus–amygdala ^{31Reference 31Jung HY et al. · 2015AnimalValerenic Acid Protects Against Physical and Psychological Stress by Reducing the Turnover of Serotonin and Norepinephrine in Mouse Hippocampus-Amygdala RegionView study →}. Human evidence lags well behind the mechanism: a Cochrane review of valerian for anxiety disorders found only one eligible trial and judged the evidence insufficient ^{15Reference 15Miyasaka LS et al. · 2006Valerian for anxiety disordersView study →}; a network meta-analysis of anxiolytic herbs did not rank valerian among the effective agents ^{16Reference 16Zhang W et al. · 2022Meta-analysisMedicinal herbs for the treatment of anxiety: A systematic review and network meta-analysisView study →}; a GAD pilot with valepotriates was underpowered and formally negative on its primary outcome ^{17Reference 17Andreatini R et al. · 2002RCTEffect of valepotriates (valerian extract) in generalized anxiety disorder: a randomized placebo-controlled pilot studyView study →}; and an EEG trial found valerian altered frontal alpha coherence but produced no between-group clinical difference versus placebo ^{19Reference 19Roh D et al. · 2019RCTValerian extract alters functional brain connectivity: A randomized double-blind placebo-controlled trialView study →}.

Gap: the mechanism is among the best-characterised in phytomedicine, but adequately powered human anxiety RCTs are essentially absent — the human case is inferred from preclinical strength.

Valerian’s antispasmodic action on smooth muscle provides a rationale for menstrual-pain relief. A double-blind RCT (n=100, 255 mg three times daily for the first three days of menstruation over two cycles) found significantly greater reduction in pain severity with valerian than placebo, attributed to its antispasmodic effect ^{21Reference 21Mirabi P · 2011Effects of valerian on the severity and systemic manifestations of dysmenorrheaView study →}. A 2025 systematic review and meta-analysis pooled five controlled trials (201 intervention, 207 control) and reported a significant pain reduction versus control (SMD −1.03, 95% CI −1.74 to −0.33), while explicitly cautioning that heterogeneity was very high (I²=90%) and the trials few and small ^{22Reference 22Rabiei F et al. · 2025Meta-analysisEffect of Valeriana officinalis on Primary Dysmenorrhea: A Systematic Review and Meta-AnalysisView study →}.

Gap: the pooled effect is meaningful but rests on a small, heterogeneous, largely single-region evidence base with variable dosing; independent replication in other populations is lacking.

Valerian has been tested for vasomotor menopausal symptoms on the premise of phytoestrogenic and calming activity. A triple-blind RCT in 60 postmenopausal women (530 mg twice daily for two months) reported significantly lower hot-flash severity at one and two months and reduced frequency at two months versus placebo ^{20Reference 20Jenabi E et al. · 2018RCTThe effect of Valerian on the severity and frequency of hot flashes: A triple-blind randomized clinical trialView study →}. A separate RCT in postmenopausal women with insomnia found improved sleep quality on the same dose, supporting a symptom-relief role in this group though not measuring flashes directly ^{9Reference 9Taavoni S et al. · 2011RCTEffect of valerian on sleep quality in postmenopausal women: a randomized placebo-controlled clinical trialView study →}.

Gap: the signal comes from small, single-region trials; the proposed phytoestrogen mechanism is asserted rather than demonstrated, and no large or multi-centre replication exists.

Valerian has a good safety profile across trials, with adverse events generally mild and comparable to placebo (headache, dizziness, gastrointestinal upset, and morning grogginess); no severe adverse events were reported across a pooled population aged 7–80 in the largest review ^{1Reference 1Shinjyo N et al. · 2020Meta-analysisValerian Root in Treating Sleep Problems and Associated Disorders — A Systematic Review and Meta-AnalysisView study →}, and regulatory assessment confirms an established safety record for short-term use ^{34Reference 34European Medicines Agency · 2016Assessment report on Valeriana officinalis L., radix and Valeriana officinalis L., aetheroleumView study →}. A small subset of people experience paradoxical stimulation — restlessness rather than sedation.

Its main practical risk is additive central-nervous-system depression: because valerenic acid potentiates GABA-A signalling, valerian should be combined cautiously with alcohol, benzodiazepines, barbiturates, opioids, sedating antihistamines and other CNS depressants ^{23,24,34Reference 23Khom S et al. · 2007Valerenic acid potentiates and inhibits GABA(A) receptors: molecular mechanism and subunit specificityView study →Reference 24Benke D et al. · 2009AnimalGABA-A receptors as in vivo substrate for the anxiolytic action of valerenic acidView study →Reference 34European Medicines Agency · 2016Assessment report on Valeriana officinalis L., radix and Valeriana officinalis L., aetheroleumView study →}. Post-marketing surveillance found that life-threatening reactions to popular herbs including valerian occurred specifically when taken alongside prescription medicines, underscoring the interaction risk rather than intrinsic toxicity ^{33Reference 33Hoban CL et al. · 2019Analysis of spontaneous adverse drug reactions to echinacea, valerian, black cohosh and ginkgo in Australia from 2000 to 2015View study →}. Because it can cause drowsiness, avoid driving or operating machinery after dosing, and the EMA advises discontinuing use about one week before surgery due to potential additive sedation with anaesthesia ^{34Reference 34European Medicines Agency · 2016Assessment report on Valeriana officinalis L., radix and Valeriana officinalis L., aetheroleumView study →}. The reactive valepotriates — much higher in the non-officinalis Indian (V. jatamansi) and Mexican (V. edulis) species — carry theoretical cytotoxicity concerns, another reason not to substitute those species for V. officinalis.

Scope note: pharmacodynamic additive CNS depression is well-supported and a pharmacovigilance signal exists for concomitant prescription use ^{33,34Reference 33Hoban CL et al. · 2019Analysis of spontaneous adverse drug reactions to echinacea, valerian, black cohosh and ginkgo in Australia from 2000 to 2015View study →Reference 34European Medicines Agency · 2016Assessment report on Valeriana officinalis L., radix and Valeriana officinalis L., aetheroleumView study →}; dedicated pharmacokinetic CYP450 interaction trials are limited and no clinically significant CYP effect is established.