Holy basil
Also called Tulsi, Ocimum tenuiflorum, Ocimum sanctum, Sacred basil, Rama tulsi. Herb (Lamiaceae leaf and aerial parts); described in Health Canada's monograph as an adaptogen in herbal medicine.
Bottom line
Holy basil (tulsi) is an aromatic herb used in Ayurveda [12]. In two placebo-controlled trials of extracts from one company, adults under stress reported larger drops in self-rated stress than with placebo [1][2], but sleep findings were mixed and mood scores did not differ from placebo [1]. Health Canada says not to use it during pregnancy [11].
- In an 8-week trial of 100 adults with stress and poor sleep, funded by the ingredient supplier Natural Remedies, Perceived Stress Scale scores fell 37% with 250 mg a day of Holixer and 19% with placebo [1].
- A 6-week trial of 150 adults with stress symptoms found larger falls in a symptom score with 1,200 mg a day of OciBest, an extract developed by Natural Remedies, whose researchers co-authored the study [2].
- In the same industry-funded Holixer trial, one self-rated sleep score fell more than with placebo, but another did not differ significantly and a wrist tracker found no difference in total sleep time or sleep efficiency [1].
- A systematic review of 24 human studies, co-authored by a paid adviser to the tulsi maker Organic India, found 15 reported no adverse events and 8 did not report on them; the longest study lasted 13 weeks [4].
- Health Canada's monograph says not to use holy basil if pregnant and to ask a practitioner first if taking heart or blood pressure medication [11].
Evidence by outcome
| Outcome | Grade | Basis | Modifiers | Rationale |
|---|---|---|---|---|
| Perceived stress | B Moderate | One randomized, double-blind, placebo-controlled RCT with n >= 100, positive on its prespecified primary outcome (PSS) and with known funding (n = 100 randomized, 85 completed; the editor counts randomized n); a second RCT, tied to the same supplier, points the same way | Industry-fundedShort-term only | Why B grade for Perceived stress: explainedApproved of the Perceived stress grade |
| Working memory | C Limited | C: one small RCT (n = 40) in healthy adults with positive results on task measures | Short-term onlySingle research group | Why C grade for Working memory: explainedApproved of the Working memory grade |
| Mood | C Limited, no effect found | One RCT null on mood measures (secondary outcomes); N needs a meta-analysis or two adequate independent null RCTs | Industry-fundedShort-term only | Why C grade for Mood: explainedApproved of the Mood grade |
| Sleep quality | C Limited, no effect found | C, direction none: one RCT with one positive secondary self-report outcome (AIS) against null RSQ, PROMIS-29 sleep disturbance and wearable-tracker measures, plus one symptom item on a scale not described as validated | Industry-fundedSubjective outcome onlyShort-term only | Why C grade for Sleep quality: explainedApproved of the Sleep quality grade |
Grades describe evidence for each outcome, not a recommendation. Open a grade for its rationale and dated grade history. How we grade
As of November 11, 2026 we found no meta-analysis of holy basil for any outcome on this page (PubMed and Europe PMC searches, November 11, 2026). A 2017 systematic review found 24 human studies of tulsi and rated only three as high quality [4]. It noted that almost all studies were run in India [4], and one of its two authors is a paid adviser to Organic India, a maker of tulsi products [4]. The grades below therefore rest on a few short trials, mostly from one supplier, and each section names the extract tested. The evidence grading method explains what each grade requires.
Does holy basil lower perceived stress?
Two trials of extracts from the same company point the same way [1][2]. In a preregistered 8-week randomized, double-blind trial funded by Natural Remedies, which also supplied the Holixer extract, 100 adults aged 18-65 were randomly assigned to 125 mg of Holixer twice daily or a placebo, and 15 withdrew (9 on placebo, 6 on holy basil) [1]. Participants had felt stressed for longer than a month, had current sleep problems and scored 14 or higher on the Perceived Stress Scale (PSS) [1].
The PSS, the trial's primary outcome, runs from 0 to 40, with higher scores meaning more perceived stress [1]. Scores fell by 37% with holy basil and by 19% with placebo [1], an average drop of 8.02 points compared with 4.28 points [1]. The gap between groups became statistically significant from week 6 [1]. Hair cortisol was lower than with placebo at week 8 [1]. In a laboratory stress test, the Maastricht Acute Stress Test, the holy basil group had lower salivary cortisol and blood pressure responses and lower self-rated stress than the placebo group [1].
An earlier 6-week randomized, double-blind trial gave 150 adults with symptoms of general stress either placebo (n = 79) or OciBest (n = 71) at 1,200 mg of actives a day [2]. Three of its authors worked at the Natural Remedies research and development center, the company that developed OciBest [2]. On a self-rated symptom scale, which the paper does not describe as a validated stress questionnaire, "forgetfulness, sexual problems of recent origin, frequent feeling of exhaustion, and frequent sleep problems of recent origin" and the total symptom score fell more than with placebo [2].
Neither trial ran longer than 8 weeks [1][2]. A smaller 30-day trial in healthy adults found no between-group difference from placebo in salivary cortisol or State-Trait Anxiety Inventory scores [3]. A 2026 trial in 186 adults with high stress found lower PSS scores than placebo at day 60 with a formula containing rhodiola, holy basil and schisandra, funded by its maker Gaia Herbs [10]. Because that formula contains several herbs, it cannot show what holy basil does on its own. For other herbs graded for stress, see ashwagandha, rhodiola and Panax ginseng, or the mood and stress hub.
Does holy basil improve sleep quality?
Evidence is mixed: one self-rated sleep scale fell more than with placebo, but other questionnaire and tracker measures showed no significant difference, so the grade shows no direction of benefit [1]. In the Holixer trial funded by Natural Remedies, scores on the Athens Insomnia Scale, a self-rated questionnaire and a secondary outcome, fell 48% from baseline in the holy basil group [1]. The difference from placebo was statistically significant at week 8 [1].
Other sleep measures in the same trial did not differ from placebo. Scores on a restorative sleep questionnaire and the PROMIS-29 sleep-disturbance subscale showed no between-group difference [1]. A wrist-worn Fitbit found no between-group difference in total sleep time or time in bed [1], and the change in sleep efficiency did not differ significantly between groups either [1]. The authors note that Fitbit devices tend to overestimate total sleep time and sleep efficiency compared with laboratory sleep studies [1], and they say research with gold-standard objective sleep measures is needed [1].
In the 6-week OciBest trial, run partly by researchers employed by Natural Remedies, which developed the extract, "frequent sleep problems of recent origin" was one of the symptom items that fell more than with placebo [2].
Does holy basil affect mood?
In the Holixer trial, funded by the ingredient supplier Natural Remedies, mood scores did not differ from placebo [1]. The change in total mood disturbance on the Profile of Mood States (POMS-A) showed no between-group difference (p = 0.695) [1]. None of the PROMIS-29 subscales differed between groups either [1]; these subscales include anxiety, fatigue and sleep disturbance [1].
These were secondary outcomes in one trial of 8 weeks [1]. That is not enough to conclude holy basil has no effect on mood, so the grade shows no direction of benefit.
Does holy basil improve working memory?
One small trial reports better scores on a working-memory task [3]. In a randomized, placebo-controlled trial, healthy adults took 300 mg a day of an ethanolic leaf extract or placebo for 30 days [3]; a systematic review lists 40 participants aged 18-30 [4]. Compared with placebo, the holy basil group had faster reaction times and lower error rates on the Sternberg test, a working-memory task, and faster responses on the Stroop test [3].
Both groups improved over the 30 days, but the placebo group's improvement leveled off after day 15 [3]. The abstract does not report effect sizes or the number of participants [3]. The review, co-authored by a paid adviser to Organic India, rated it high quality, with a Jadad score of 5 [4]. The Stroop results measure executive function and are not graded separately on this page.
What the evidence does not show
- What holy basil does on its own, from combination products. A 12-week trial of a multi-ingredient herbal blend containing holy basil, in 128 adults aged 55-75 with subjective memory complaints, found faster task performance but also memory deficits, and was funded by the blend's maker, Pukka Herbs [9]. The authors say an unequal randomization limits how the memory results can be read [9]. The daily dose of two capsules held 86 mg of holy basil, 43 mg per capsule [9], and the results cannot be attributed to holy basil alone.
- Immune outcomes in healthy people. A 4-week crossover trial in 24 healthy volunteers found changes in immune cell and cytokine markers with 300 mg capsules of an ethanolic leaf extract compared with placebo [7]. Immune markers are not graded on this site.
- Long-term effects. The longest study in the 2017 systematic review, co-authored by a paid adviser to Organic India, lasted 13 weeks [4].
Doses used in studies
Ranges researchers used, not dosing advice. Bars share one scale. Read our disclaimer.
2-3 g/day (dry or powdered leaf, or non-standardized ethanolic extracts); 4.2-28 g/day (non-standardized aqueous extracts)
Timing and form
As of November 11, 2026 we found no human pharmacokinetic study of holy basil (PubMed search, November 11, 2026), so its onset and half-life are not known from the sources we checked. Health Canada's monograph covers oral dried leaf, powdered leaf and non-standardized ethanolic or aqueous extracts [11], and it excludes foods and food-like forms [11].
The trials gave capsules daily for 4 to 8 weeks [1][2][3]; the first two were tied to Natural Remedies [1][2]. Timing differed between trials: the review (co-authored by an Organic India adviser) lists the healthy-adult trial as taken before meals and the OciBest trial as taken after meals [4], and the immune trial gave capsules on an empty stomach [7]. None of these trials compared timings.
What it is
Holy basil (Ocimum tenuiflorum, also listed as Ocimum sanctum) is an aromatic herb used in traditional Indian medicine, known as Ayurveda [12]. It is not the same plant as the basil widely used in south Asian cooking [12].
The leaf, dried or fresh, is the part most often used [4]. Supplements come as tablets, capsules, eye drops and liquid extracts [12].
Health Canada's monograph lets licensed products state that holy basil is "used in Herbal Medicine as an adaptogen to help increase energy and resistance to stress over time" [11]. That is permitted label wording for licensed products, not trial evidence of an effect.
The two single-herb stress trials on this page used branded, standardized extracts, which differ from each other. Holixer is a hydroalcoholic extract of the leaves and aerial parts [1], standardized to at least 5% of what its maker calls the Ocimum Bioactive Complex [1]. OciBest is a whole-plant extract developed by Natural Remedies [2], standardized to rosmarinic acid above 0.2% and triterpene acids above 2.5% [2]. Two trials in healthy volunteers used an ethanolic leaf extract [3][7].
How it may work (mechanism, not effect): MSKCC lists eugenol, carvacrol, ursolic acid, β-caryophyllene, orientin, vicenin and rosmarinic acid among its active constituents [12]. MSKCC says the proposed anti-stress action involves inhibiting cortisol release and blocking the corticotropin-releasing hormone receptor [12]. A systematic review of 52 randomized trials of plant products and stress-axis (HPA-axis) hormones, which included holy basil, concluded that for most phytonutrients the effect on these hormones in humans is unclear [6].
Safety and interactions
Safety flag. A systematic review of 24 human studies, co-authored by a paid adviser to Organic India, found 15 reported no adverse events and 8 did not report on them; the longest study lasted 13 weeks [4]. In the 8-week Holixer trial, funded by Natural Remedies, no serious adverse events were reported and adverse-effect frequency was similar to placebo; one participant withdrew with increased agitation [1]. Health Canada's monograph says not to use holy basil if pregnant and to ask a practitioner first if breastfeeding [11]. A review reports that reproduction and fertility studies are inadequate and that holy basil is not recommended for children or during pregnancy or lactation above dietary amounts [5].
Who sources say should be careful.
- People who are pregnant: Health Canada's monograph says "Do not use if you are pregnant" [11]. A review by two Procter & Gamble researchers reports that, because of traditional use as an abortifacient and conflicting reports on embryo toxicity, holy basil is not recommended during pregnancy above amounts expected from the diet [5].
- People who are breastfeeding: Health Canada asks them to consult a practitioner before use [11], and the review does not recommend it during lactation above dietary amounts [5]. The Holixer trial excluded pregnant and breastfeeding women [1].
- Children: Health Canada's monograph covers adults 18 years and older [11], and the review does not recommend it for children above dietary amounts [5].
- People with a heart condition or diabetes, or taking heart or blood pressure medication: Health Canada asks them to consult a practitioner first [11].
Short trials report few side effects. A 2017 systematic review found that 15 of 24 human studies reported no adverse events and 8 did not describe adverse events at all [4]. Only one study, in 16 adults with obesity taking a 250 mg leaf extract capsule twice daily, reported occasional nausea [4]. The longest study lasted 13 weeks, so long-term side effects cannot be ruled out [4]. One of the review's authors is a paid adviser to Organic India, a tulsi maker [4].
In the 8-week Holixer trial, funded by Natural Remedies, no serious adverse events were reported, and the frequency of adverse effects was similar in both groups [1]. Digestive disturbances were reported 5 times in each group, and headache 2 times on placebo and 3 times on holy basil [1]. One person taking holy basil withdrew because of increased agitation, and one taking placebo withdrew because of nausea [1]. The OciBest trial, three of whose authors worked for Natural Remedies, reported no adverse events [2]. MSKCC lists nausea, headache and agitation as reported adverse reactions [12].
A 2021 review by two researchers employed by Procter & Gamble reports no genotoxicity on a bone marrow micronucleus test in rats given up to 5 g/kg body weight a day for 7 days [5]. The same review notes that EFSA lists dried holy basil leaf extract among botanicals with a possible reproductive toxicity concern [5], and that reproduction and fertility studies are inadequate, leaving a data gap [5].
Blood glucose may be affected. In a randomized, single-blind crossover trial in adults with type 2 diabetes, a clinical population, fasting blood glucose fell by 21.0 mg/dl [8] and post-meal glucose by 15.8 mg/dl compared with placebo leaves [8]. Results may not apply to healthy adults. Health Canada cites this trial as a source for its diabetes and heart-medication cautions [11]. As of November 12, 2026 we found no LiverTox chapter for holy basil (NCBI Books search, November 12, 2026).
Interactions sources report
As of November 11, 2026 we found no human pharmacokinetic or herb-drug interaction study of holy basil (PubMed searches, November 11, 2026). The interaction cautions below come from Health Canada's monograph, not from interaction trials.
- Heart and blood pressure medicines: Health Canada asks people taking any heart or blood pressure medication to ask a health care practitioner before use [11]. In the Holixer trial (funded by Natural Remedies), which enrolled adults who had been medication free for at least 3 months [1], systolic and diastolic blood pressure responses to a laboratory stress test were lower than with placebo [1]. That was a stress-test response, not resting blood pressure, in people taking no medicines.
- Diabetes: Health Canada also asks people with diabetes or a heart condition to ask a practitioner before use [11], and it cites the crossover trial in which blood glucose fell with holy basil leaves [8][11].
If you take any of these medicines, talk to your doctor or pharmacist before combining them with holy basil.
Regulatory status
| Market | Status | Notes |
|---|---|---|
| US | No FDA statement specific to holy basil found as of November 11, 2026; FDA does not approve dietary supplements before they are marketed. | |
| UK | Not verified as of November 11, 2026. We checked the GB nutrition and health claims register (updated May 19, 2026), which has no holy basil, tulsi or Ocimum entries, and could not confirm GB food or supplement status. | |
| Canada | Covered by Health Canada's holy basil leaf monograph dated February 27, 2026, a guide for natural health product licence applications (adults 18 and over, oral, dried leaf preparations), with a pregnancy contraindication. | |
| Australia | Listed as permissible ingredient item 3538 (purposes A, H; A means active ingredient) in the Therapeutic Goods (Permissible Ingredients) Determination (No. 3) 2026, registered October 13, 2026, with eugenol requirements for oil or distillate. | |
| EU | EU Novel Food Catalogue entry (last modified October 19, 2023): aerial parts not novel in food; seeds a novel food not yet authorized. |
FAQ
Is holy basil the same as the basil used in cooking?
No. MSKCC notes that holy basil should not be confused with the basil widely used in south Asian cuisine [12]. Holy basil is Ocimum tenuiflorum, also listed as Ocimum sanctum [12][15].
How much holy basil did studies use?
The Holixer trial used 125 mg twice daily [1], the OciBest trial used 1,200 mg of actives a day [2], and a trial in healthy young adults used 300 mg a day of an ethanolic leaf extract [3]. Health Canada's monograph sets 2-3 g a day of dried leaf for licensed adaptogen products made from dry or powdered leaf or non-standardized ethanolic extracts [11]. These are study and licensing doses, not advice.
Does holy basil help with sleep?
Evidence is mixed. In one industry-funded trial, one self-rated sleep score fell more than with placebo, another showed no significant difference, and tracker-measured total sleep time and sleep efficiency did not differ [1]. The trial authors say objective sleep measures are needed [1].
Is holy basil safe during pregnancy?
Health Canada's monograph states 'Do not use if you are pregnant' and asks people who are breastfeeding to consult a practitioner before use [11]. A review by two Procter & Gamble researchers reports that reproduction and fertility studies are inadequate and that holy basil is not recommended during pregnancy or lactation above dietary amounts [5].
Who funded the holy basil trials?
The Holixer trial was funded by Natural Remedies, which supplied the extract [1], and three authors of the OciBest trial worked for Natural Remedies, which developed that extract [2]. Combination-product trials were funded by Pukka Herbs and Gaia Herbs [9][10].
References
- Lopresti AL, Smith SJ, Metse AP, et al. A randomized, double-blind, placebo-controlled trial investigating the effects of an Ocimum tenuiflorum (Holy Basil) extract (HolixerTM) on stress, mood, and sleep in adults experiencing stress. Front Nutr. 2022.
- Saxena RC, Singh R, Kumar P, et al. Efficacy of an Extract of Ocimum tenuiflorum (OciBest) in the Management of General Stress: A Double-Blind, Placebo-Controlled Study. Evid Based Complement Alternat Med. 2012.
- Sampath S, Mahapatra SC, Padhi MM, et al. Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific cognitive parameters in healthy adult volunteers: A placebo controlled study. Indian J Physiol Pharmacol. 2015.
- Jamshidi N, Cohen MM. The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature. Evid Based Complement Alternat Med. 2017.
- Roe AL, Venkataraman A. The Safety and Efficacy of Botanicals with Nootropic Effects. Curr Neuropharmacol. 2021.
- Lopresti AL, Smith SJ, Drummond PD. Modulation of the hypothalamic-pituitary-adrenal (HPA) axis by plants and phytonutrients: a systematic review of human trials. Nutr Neurosci. 2022.
- Mondal S, Varma S, Bamola VD, et al. Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers. J Ethnopharmacol. 2011.
- Agrawal P, Rai V, Singh RB. Randomized placebo-controlled, single blind trial of holy basil leaves in patients with noninsulin-dependent diabetes mellitus. Int J Clin Pharmacol Ther. 1996.
- Wightman E, Khan J, Smith E, et al. Chronic supplementation of a multi-ingredient herbal supplement increases speed of cognitive task performance alongside changes in the urinary metabolism of dopamine and the gut microbiome in cognitively intact older adults experiencing subjective memory decline: a randomized, placebo controlled, parallel groups investigation. Front Nutr. 2023.
- McKinney E, Stewart J, Kewalramani R, et al. Effects of multi-herb and ashwagandha root formulas on stress modulation: a randomized, double-blind, placebo-controlled clinical study. Trials. 2026.
- Health Canada, Natural Health Products Ingredients Database. Holy basil - Ocimum tenuiflorum - Leaf (monograph). Updated February 27, 2026.
- Memorial Sloan Kettering Cancer Center (MSKCC), About Herbs. Holy Basil. Updated September 21, 2026.
- U.S. Food and Drug Administration. Questions and Answers on Dietary Supplements. Updated August 27, 2026.
- GOV.UK (Department of Health and Social Care). Great Britain nutrition and health claims (NHC) register. Updated May 19, 2026.
- European Commission, DG SANTE. EU Novel Food Catalogue: Ocimum tenuiflorum L. (POL-NF-00543). Updated October 19, 2023.
- Australian Government, Federal Register of Legislation (TGA instrument). Therapeutic Goods (Permissible Ingredients) Determination (No. 3) 2026 (F2026L01382). Updated October 13, 2026.