Supplements for Anxiety: What the Trials and Guidelines Show

Most supplements for anxiety have little rigorous evidence behind them, and only a few have enough trial data to grade^[1]. The most complete review is a 2022 guideline from the World Federation of Societies of Biological Psychiatry (WFSBP) and the Canadian Network for Mood and Anxiety Treatments (CANMAT), written by a taskforce of 31 academics and clinicians from 15 countries^[1].

For anxiety disorders, the taskforce found modest support for ashwagandha and lavender (both rated "provisionally recommended") and weaker support for galphimia, another herbal extract^[1]. It rated kava "not recommended" and chamomile "not currently recommended" for generalized anxiety disorder (GAD)^[1].

The nutrient side came up short. Apart from N-acetyl cysteine, which was weakly recommended for OCD-related disorders, "no other nutraceutical had sufficient evidence in any anxiety-related disorder," the guideline states^[1]. That covers popular choices such as magnesium, vitamin D and probiotics.

The taskforce also said supplements with supportive evidence should be used mainly as add-ons within standard medical care, especially for more severe illness, and flagged inconsistent product quality and standardization as a key limit on confidence^[1]. Prevalence figures for anxiety itself are on the anxiety statistics page; this article covers the supplement evidence only.

Silexan is a proprietary oral preparation made from Lavandula angustifolia oil. A 2023 meta-analysis pooled all five completed double-blind trials, covering 1,213 adult outpatients with subthreshold anxiety, mixed anxiety and depression, or GAD, who took 80 mg a day or placebo for 10 weeks^[2].

By the end, 51.8% of the Silexan groups had cut their Hamilton Anxiety Rating Scale (HAMA) score by at least half, compared with 38.8% on placebo, a risk ratio of 1.34^[2]. The authors calculated that 8 people would need treatment for one additional responder^[2].

Adverse events, serious adverse events and dropouts for side effects did not differ significantly between groups; serious events occurred in 1.0% of Silexan users and 0.8% of placebo users^[2].

Two caveats apply. One co-author is an employee of the extract's manufacturer, Dr. Willmar Schwabe, and several others reported fees from the company^[2]. The trials also tested one standardized extract at one dose, so they say nothing directly about lavender teas, diffusers or other lavender oil products.

Ashwagandha

Ashwagandha (Withania somnifera) received the same "provisionally recommended" rating as lavender for anxiety disorders^[1]. The individual trials, dosing, and liver and thyroid safety signals are covered in ashwagandha for anxiety.

Omega-3 fatty acids (fish oil)

A 2018 JAMA Network Open meta-analysis pooled 19 clinical trials with 2,240 participants from 11 countries and found omega-3 treatment was associated with greater improvement in anxiety symptoms than control treatments (Hedges g, 0.374)^[3]. The average dose was about 1,606 mg a day^[3].

The benefit was statistically significant only in subgroups taking at least 2,000 mg a day, and it was larger in people with a clinical diagnosis than in people without one^[3]. The WFSBP/CANMAT taskforce still did not find enough evidence to recommend omega-3s for any anxiety-related disorder^[1].

Saffron

A meta-analysis of six trials found saffron reduced anxiety symptoms compared with placebo (SMD 0.95), a large effect on paper^[4]. The same review flagged very high heterogeneity (I² of 89%) and possible publication bias, and most saffron research has been conducted in Iran^[4]. The guideline rated saffron for depression, not anxiety^[1].

Kava

For kava (Piper methysticum), the most recent pooled data show no effect in GAD: four trials produced a standardized mean difference of −0.02^[4]. The guideline rated it "not recommended" for GAD^[1].

NCCIH reports that kava products have been linked to rare cases of liver injury, some serious or fatal, and that kava should not be combined with other sedating substances such as benzodiazepines or alcohol^[5].

Chamomile

The taskforce rated chamomile "not currently recommended" (+/-) for GAD, a grade that falls short of a recommendation in either direction^[1].

L-theanine

L-theanine is an amino acid from green tea. A 2026 meta-analysis of 31 randomized trials (1,168 participants) found anxiety effects were "inconsistent and non-significant," with the only positive anxiety result coming from a single study in people with psychotic disorders^[6].

The same review found a modest reduction in acute stress after a single dose (SMD 0.31), but that result leaned heavily on studies at high risk of bias^[6]. No serious adverse events were reported^[6].

Magnesium and vitamin D

Neither magnesium nor vitamin D met the guideline's evidence bar for any anxiety disorder^[1]. Vitamin D was weakly recommended for depression, not for anxiety^[1]. The magnesium trial record, including which forms were studied, is in magnesium for anxiety.

Probiotics

A 2019 meta-analysis of 34 controlled trials found probiotics had a small but statistically significant effect on anxiety (d = −0.10), while prebiotics did not differ from placebo^[7]. The authors noted that the pooled effects were held down by a shortage of trials in clinical samples^[7].

Valerian, passionflower, melatonin and B vitamins

These products are widely sold for calm, but none received a supportive rating for an anxiety disorder in the 2022 guideline, which graded only ashwagandha, galphimia and lavender positively for anxiety^[1]. A 2021 meta-review listed passionflower among plant medicines with supportive or mixed trial evidence in affective disorders that had not yet been pooled in a meta-analysis^[4].

Supplement use is widespread. In 2017–2018, 57.6% of U.S. adults aged 20 and over reported using at least one dietary supplement in the past 30 days, including 63.8% of women and 50.8% of men^[9].

No FDA approval before sale

Under the Dietary Supplement Health and Education Act (DSHEA) of 1994, the FDA "does not have the authority to approve dietary supplements before they are marketed"^[8]. Manufacturers are responsible for safety, and the FDA is largely limited to enforcement after a product is on shelves^[8].

The required label disclaimer must state that the product is not intended to "diagnose, treat, cure, or prevent any disease," because only a drug can legally make that claim^[8].

Hidden drug ingredients

From 2007 through 2016, the FDA identified 776 dietary supplements containing unapproved drug ingredients, and in 97.6% of cases those ingredients were not on the label^[10]. Most were sold for sexual enhancement, weight loss or muscle building rather than anxiety, but the pattern shows that what a label lists and what a bottle contains can differ^[10].

Emergency visits and drug interactions

A 2015 analysis of a nationally representative sample of U.S. emergency departments (2004 through 2013) estimated about 23,005 U.S. emergency department visits a year for adverse events tied to dietary supplements, leading to an estimated 2,154 hospitalizations a year^[11]. Weight-loss and energy products were most often implicated^[11].

Interactions are a separate risk. St. John's wort, sometimes taken for mood, can weaken birth control pills, warfarin, some antidepressants and several heart, HIV and transplant drugs, and taking it with serotonin-affecting medicines may cause serious serotonin-related side effects^[12]. NCCIH also advises against combining kava with benzodiazepines or alcohol^[5].

Trial lengths give the best guide to timing. The Silexan trials measured results after 10 weeks^[2], kava trials in the meta-review ran 3 to 8 weeks^[4], and NCCIH notes that kava may need to be taken for several weeks to produce an effect^[5]. L-theanine's clearest single-dose effects were measured 30 to 60 minutes after a 200 mg dose, and they concerned attention rather than anxiety^[6].

No supplement in this review has been shown to replace standard treatment. The WFSBP/CANMAT guideline positions supported supplements as adjuncts within professional care rather than stand-alone treatments^[1], and the omega-3 authors called for trials of omega-3s both alone and added to standard therapy^[3].

The evidence for the established options is covered in therapy for anxiety, anxiety medication and SSRIs for anxiety. Non-drug techniques with trial data are reviewed in coping tools for anxiety.