Obsessive-compulsive disorder (OCD)

Overview

All listed OCD supplements have low-strength evidence. N-Acetyl Cysteine (NAC) (WA 52; low effect size, high evidence, medium trust) may reduce some symptoms when added to influenzavoxamine in adults but showed no benefit in larger trials with other medications; one small pediatric study was suggestive. Inositol (WA 44; low effect size, low evidence, medium trust) had mixed results across two small trials. Ashwagandha (WA 44; low effect size, low evidence, medium trust), Milk Thistle (WA 44; low effect size, low evidence, medium trust), and Theanine (WA 44; low effect size, low evidence, medium trust) each have single small studies with uncertain benefit.

No supplement has reliable evidence for OCD. The heatmap and evidence reviews below summarize individual trials.

Effect graph

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Relevant supplements

Relevant supplements sorted by DEX Score.


N-Acetyl Cysteine (NAC)	★★★★★	Low
Valerian	★★★★★	Low
Theanine	★★★★★	Low
Milk Thistle	★★★★★	Low
Inositol	★★★★★	Low
Ashwagandha	★★★★★	Low

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Studies

Find individual evidence reviews for supplements sorted by DEX Score.

6 supplements for rated at least stars. All purchase bands. No minimum star filter.

N-Acetyl Cysteine (NAC)View supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceHighTrustMedium

Evidence Review

N-acetylcysteine (NAC) might help reduce some OCD symptoms when taken with fluvoxamine in adults, but it doesn’t seem to help with compulsions or increase the chance of getting better overall.
Larger studies with adults taking other psychiatric medications did not find NAC improved OCD symptoms or related issues.
A small study in children not on psychiatric medications suggested NAC might reduce symptoms but more evidence is required.

Browse 5 studies

RCTN-acetyl cysteine (NAC) augmentation in the treatment of obsessive-compulsive disorder: A phase III, 20-week, double-blind, randomized, placebo-controlled trial2022n=98

A phase III 20-week RCT of 98 OCD patients found NAC augmentation (2–4 g/day) did not reduce Y-BOCS scores versus placebo.

Effect: No Benefit
Duration: 20 weeks
Dose: 4 g/day
Participants: 98

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Controlled trialN-Acetylcysteine for Pediatric Obsessive-Compulsive Disorder: A Small Pilot Study2020n=11

A small pilot RCT of 11 children with OCD found NAC (up to 2700 mg/day for 12 weeks) significantly reduced CY-BOCS scores versus placebo despite early stopping.

Effect: Benefit
Dose: 2700 mg/day
Population: Adults
Participants: 11
Ages: 8–17

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RCTRandomized, Double-Blind, Placebo-Controlled Trial of N-Acetylcysteine Augmentation for Treatment-Resistant Obsessive-Compulsive Disorder2017n=40

A 16-week RCT of 40 treatment-resistant OCD patients found NAC (3000 mg/day) produced no significant Y-BOCS improvement versus placebo.

Effect: No Benefit
Duration: 16 weeks
Dose: 3000 mg/day
Population: Adults
Participants: 40
Ages: 18–65

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RCTN-acetylcysteine augmentation therapy for moderate-to-severe obsessive-compulsive disorder: randomized, double-blind, placebo-controlled trial2016n=44

A 10-week RCT of 44 OCD patients on fluvoxamine found NAC augmentation (2000 mg/day) significantly improved Y-BOCS scores versus fluvoxamine plus placebo.

Effect: Benefit
Duration: 10 weeks
Dose: 2000 mg/day
Population: Patients with obsessive-compulsive disorder
Participants: 44

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RCTN-acetylcysteine add-on treatment in refractory obsessive-compulsive disorder: a randomized, double-blind, placebo-controlled trial2012n=48

A 12-week RCT of 48 refractory OCD patients found NAC add-on (up to 2400 mg/day) significantly reduced Y-BOCS scores, with 52.6% achieving full response.

Effect: Benefit
Duration: 12 weeks
Dose: 2400 mg/day
Population: Women
Participants: 48
Avg age: ~31

View on PubMed

AshwagandhaView supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Evidence Review

It is uncertain if ashwagandha helps obsessive-compulsive disorder (OCD).
One small study found that taking increasing doses of ashwagandha for 6 weeks along with standard OCD medication might reduce symptoms more than medication alone.
However, the study had some issues with initial symptom differences between groups.

Browse 1 study

RCTEvaluation of the efficacy of Withania somnifera (Ashwagandha) root extract in patients with obsessive-compulsive disorder: A randomized double-blind placebo-controlled trial2016n=15

In 30 OCD patients on SSRIs, adjunctive ashwagandha 120 mg/day improved Yale-Brown scores more than SSRIs alone over 6 weeks.

Effect: Benefit
Duration: 6 weeks
Dose: 120 mg/day
Population: OCD patients
Participants: 15

View on PubMed

InositolView supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Evidence Review

Early studies on inositol for OCD show mixed results.
Taking a high dose (18 grams daily for 6 weeks) improved symptom scores in one study, but it did not help people already on an antidepressant (SSRI).
Both studies were small and short, so the evidence is uncertain.

Browse 2 studies

RCTInositol versus placebo augmentation of serotonin reuptake inhibitors in the treatment of obsessive-compulsive disorder: a double-blind cross-over study1999

In 10 OCD patients on SSRIs over 6 weeks, inositol augmentation (18 g/day) did not significantly improve OCD symptoms versus placebo.

Effect: No Benefit
Duration: 6 weeks
Dose: 18 g/day
Population: OCD patients

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RCTInositol treatment of obsessive-compulsive disorder1996

In 13 OCD patients over 6 weeks, inositol monotherapy (18 g/day) significantly reduced Yale-Brown Obsessive-Compulsive Scale scores versus placebo.

Effect: Benefit
Duration: 6 weeks
Dose: 18 g/day
Population: Depression patients

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Milk ThistleView supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Evidence Review

It is unclear whether milk thistle helps with obsessive-compulsive disorder (OCD).
Early research suggests that milk thistle taken three times daily for 8 weeks reduces OCD symptoms about as much as the common medication fluoxetine (Prozac).
However, the studies are small and more research is needed to be sure.
Side effects may be similar to those of regular medications for OCD.

Browse 1 study

RCTComparison of Silybum marianum (L.) Gaertn. with fluoxetine in the treatment of Obsessive-Compulsive Disorder2010

An 8-week RCT found 600 mg/day silymarin produced OCD symptom reductions comparable to fluoxetine with a favorable safety profile.

Effect: Benefit
Duration: 8 weeks
Dose: 600 mg/day
Population: Adults

View on PubMed

TheanineView supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Evidence Review

It is not clear if taking L-theanine by mouth helps with obsessive-compulsive disorder (OCD).
One small study found that adding L-theanine twice daily to OCD medicine reduced obsessive thoughts and increased full treatment response.
However it did not help compulsive behaviors or overall recovery rates.

Browse 1 study

RCTL-theanine combination therapy with fluvoxamine in moderate-to-severe obsessive-compulsive disorder: A placebo-controlled, double-blind, randomized trial2023

An RCT of 50 OCD patients found that 100 mg/day L-theanine adjunct to fluvoxamine significantly improved obsession subscale scores and complete response rate versus placebo.

Effect: Benefit
Duration: 10 weeks
Dose: 100 mg/day
Population: Patients with obsessive-compulsive disorder
Ages: 18–60

View on PubMed

ValerianView supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Evidence Review

In a small 8-week study, people with obsessive-compulsive disorder who took valerian root extract showed greater improvement in their symptoms compared to those who took a placebo.
The valerian group also reported feeling sleepier, but no other major side effects were found.

Browse 1 study

RCTExtract of valerian root (Valeriana officinalis L.) vs. placebo in treatment of obsessive-compulsive disorder: a randomized double-blind study2011

An 8-week double-blind pilot RCT in adults with OCD found valerian extract 765 mg/day significantly reduced symptom scores versus placebo (P=0.000), with somnolence as the main side effect (P=0.02).

Effect: Benefit
Duration: 8 weeks
Dose: 765 mg/day
Population: Adults

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Evidence visualised

Same ratings as above, aggregated so you can see coverage and imbalance.

Purchase-guidance distribution

How many supplements fall in each purchase band

Effect-size distribution

How large the reported benefits tend to be

Study distribution across 6 supplements for obsessive-compulsive disorder (ocd) (11 studies total).
Supplement	DEX	Studies	Share
N-Acetyl Cysteine (NAC)	★★★★★52%	5	45%
Inositol	★★★★★44%	2	18%
Ashwagandha	★★★★★44%	1	9%
Milk Thistle	★★★★★44%	1	9%
Theanine	★★★★★44%	1	9%
Valerian	★★★★★44%	1	9%

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Obsessive-compulsive disorder (OCD)

Overview

Effect graph

Relevant supplements

Studies

Evidence visualised

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