Holy Basil
In short
Summary of findings for quick reference
Holy Basil (Ocimum tenuiflorum, Tulsi) combines religious significance with a long Ayurvedic tradition. Charaka Samhita mentions Surasa, now identified with Tulsi, for cough and breathing complaints. Contemporary literature also describes it as a rasayana, a traditional tonic. In India it is grown near homes and temples, with leaves used for complaints including colds. The history documented here is centred on South and Southeast Asia; historical significance is distinct from clinical evidence.
Volume II of the Ayurvedic Pharmacopoeia of India contains separate Tulsi whole-plant and leaf monographs. Other references include WHO’s Folium Ocimi Sancti monograph and Health Canada’s leaf monograph. They distinguish traditional uses, preparations and precautions. Health Canada includes an adaptogen use. These documents are not EU authorisations and do not make different leaf powders and extracts interchangeable.
Small trials by Saxena and colleagues (2012) and Lopresti and colleagues (2022) found improvements in stress symptoms with specific extracts. These findings cannot be transferred to every cup of Tulsi tea. Preliminary human findings also suggest glucose lowering, so people taking diabetes medication should seek medical advice before medicinal use. Laboratory findings on eugenol raise a theoretical interaction concern with blood thinners. Tulsi should not be used medicinally during pregnancy; WHO also advises against use while breastfeeding.
Clinical evidence ↔ Historical significanceWe display two separate evidence categories: clinical evidence from modern trials and historical significance from documented healing tradition. Both are valuable, but they answer different questions.Read more
In every encyclopedia entry we evaluate two distinct categories of evidence. Clinical evidence as used in trials meets a narrower but scientifically essential bar. At the same time, the hundreds of thousands of plant species worldwide have only partially been captured and tested in modern studies.
Alongside the trial picture our researchers compile a comprehensive overview of where and since when a plant has been used across different traditions of natural medicine. When a plant has been used as a medicinal plant in many cultures across many generations, that historical significance deserves to be visible too.
Our position: a truly informative overview emerges only when both categories sit side by side. We communicate transparently what counts as what.
Overview
Holy Basil (Ocimum tenuiflorum, synonym Ocimum sanctum), also called Tulsi, is an aromatic mint-family plant. Its native range extends from tropical and subtropical Asia to the western Pacific. Eugenol can contribute to the clove-like leaf aroma; essential-oil composition varies. Tulsi has a long Ayurvedic tradition and is grown as a sacred Hindu plant in temple courtyards and at household shrines.
Contemporary Ayurvedic literature describes Tulsi as a rasayana, a traditional tonic for resilience and well-being. Modern herbal practice often uses the label adaptogen. Neither term alone establishes clinical efficacy. Small, short trials of specific Tulsi extracts provide preliminary signals for stress symptoms. Reviews by Cohen (2014) and Jamshidi and Cohen (2017) discuss the traditional and research context; reliable evidence for long-term use remains limited.
History
Tulsi has a longstanding place in Indian culture. Its name is often translated as “the incomparable one.” In Hindu tradition it is sacred and associated with the goddess Lakshmi. Plants are tended in temple courtyards and at household shrines such as a Tulsi Vrindavan. Leaves are used in religious rituals and Ayurvedic preparations.
Charaka Samhita, Sutrasthana 27.169, mentions Surasa, now identified with Tulsi, for complaints including cough and breathing difficulties. This passage does not establish a rasayana classification or a general rejuvenating effect. Contemporary Ayurvedic literature describes Tulsi as a rasayana. The modern term adaptogen comes from a different research tradition and refers to plants proposed to support adaptation to stress. These concepts describe a context of use without establishing the efficacy of a particular preparation.
Mechanism
The leaves contain compounds including eugenol, ursolic acid, rosmarinic acid and caryophyllene. Eugenol can form a large share of the essential oil and contribute to the clove-like aroma, but composition varies substantially and other compounds may predominate. Ursolic acid is a triterpene and rosmarinic acid a polyphenol. Several of these compounds have been investigated for antioxidant and inflammation-related effects in laboratory experiments.
Proposed effects on the stress response have mainly been investigated in animal models, focusing on the hypothalamic-pituitary-adrenal axis and antioxidant processes. A small 2022 human trial also examined cortisol and responses to an experimental stress test. These individual findings do not establish the mechanism, and it remains unclear whether tea produces the same effects as the tested extract.
Saxena and colleagues tested a standardised whole-plant Tulsi extract (OciBest) in 2012. Of 158 randomised adults, 150 were analysed. Self-rated stress symptoms decreased more than with placebo over six weeks, using a study-specific symptom scale. In 2022, Lopresti and colleagues also found improvements in perceived stress in 100 adults over eight weeks, but used a different extract from leaf-rich aerial parts. Both trials provide preliminary evidence for their specific preparations.
Cohen’s 2014 review describes Tulsi in its Ayurvedic context. Jamshidi and Cohen (2017) summarised 24 human studies of varying preparations lasting two to thirteen weeks. Their review included Ocimum gratissimum, a different species known as Vana Tulsi, as well as Ocimum tenuiflorum. Its total study count therefore does not represent evidence for any single Tulsi preparation. Limited study quality and short observation periods restrict conclusions about long-term benefit and safety.
Evidence
| Outcome | Class | Grade | Effect | Studies | Refs |
|---|---|---|---|---|---|
| Mental stress symptoms (adaptogen-style use)Saxena et al. (2012) tested whole-plant OciBest: 150 of 158 randomised adults were analysed, with greater improvement in self-rated stress symptoms than placebo after six weeks. Lopresti et al. (2022) found lower perceived stress with a different extract over eight weeks. Small trials and different preparations limit generalisation.Adults with self-reported stress symptoms | EmergingEmerging research. Early small trials suggest an effect but await replication. | CEvidence quality grade C. Mixed or limited evidence. Small trials, signals, or traditional use under an EMA HMPC traditional-use monograph. This is an evidence rating, not a product endorsement. | Modest Improvement | [1][2] | |
| Blood glucose controlA small randomised crossover trial by Agrawal et al. (1996) found lower fasting and postprandial blood glucose with Tulsi leaves. The 2017 review includes further methodologically varied trials. This is insufficient for a reliable treatment recommendation; seek medical advice before use with diabetes medication.Adults with type 2 diabetes or impaired glucose tolerance | EmergingEmerging research. Early small trials suggest an effect but await replication. | DEvidence quality grade D. Preliminary signal. A single small trial, pilot result, or laboratory or animal model. Clinical relevance unclear. This is an evidence rating, not a product endorsement. | Mixed Effect | [3][5] | |
| Ayurvedic rasayana (rejuvenative) useContemporary Ayurvedic accounts describe Tulsi as a rasayana, a traditional tonic for resilience and well-being. The Charaka passage checked here concerns respiratory complaints, not rejuvenation. This cultural classification and Cohen’s 2014 review do not establish a clinical rejuvenating effect.General adult population in Ayurvedic practice | TraditionalTraditional use. Long-standing folk practice or EMA HMPC traditional-use monograph. | DEvidence quality grade D. Preliminary signal. A single small trial, pilot result, or laboratory or animal model. Clinical relevance unclear. This is an evidence rating, not a product endorsement. | Traditional Use | [6][5] | |
| Antioxidant activity (in vitro)Kelm et al. (2000) investigated compounds from fresh Tulsi leaves and stems, including eugenol and rosmarinic acid. Several showed antioxidant activity in vitro. This does not establish a health benefit from Tulsi tea or extract in humans.Laboratory assays (in vitro) | TraditionalTraditional use. Long-standing folk practice or EMA HMPC traditional-use monograph. | DEvidence quality grade D. Preliminary signal. A single small trial, pilot result, or laboratory or animal model. Clinical relevance unclear. This is an evidence rating, not a product endorsement. | Lab Signal Only | [4] |
Usage
Forms and preparation
Tulsi is available as fresh- or dried-leaf tea, leaf powder, tincture or extract, sometimes in capsules. For tea, follow the package directions for leaf quantity and steeping time. Pour freshly boiling water over the leaves and steep for at least five minutes, keeping the cup covered. The aroma varies and is often strongly clove-like. For capsules, check whether the contents are leaf powder or extract. Compare the plant part and extraction details as well as the milligram amount. Honey or fresh ginger can be added to tea to taste.
Dosage
Dose depends on plant part and preparation. For dried leaf or leaf powder, Health Canada lists 2 to 3 g daily for adults aged 18 and over. The Saxena trial instead used 1200 mg of OciBest whole-plant extract daily for six weeks; Lopresti used 250 mg daily of a different extract for eight weeks. These extract quantities are not interchangeable with one another or with the same weight of leaf powder or tea. Follow the directions for the specific preparation and its safety precautions. Short trials do not establish the safety of indefinite daily use. Seek medical or pharmacy advice before extended medicinal use or if you take regular medication.
Safety
Look-alikes
Similar plants and look-alikes
Sweet Basil (Ocimum basilicum)
Sweet Basil (Ocimum basilicum) is a different species in the same genus. Appearance and aroma vary among forms of both species. Tulsi also has culinary uses, for example as kaphrao in Thailand. Medicinal findings for one species cannot be transferred to the other.
FAQs
What is the difference between Holy Basil and Sweet Basil?
Holy Basil (Ocimum tenuiflorum, Tulsi) and Sweet Basil (Ocimum basilicum) are distinct mint-family species, both with culinary uses. Tulsi often smells clove-like, but aroma alone is not a reliable distinction because forms vary. Exact species matters for medicinal use: study findings cannot be transferred.
What does "adaptogen" mean?
Adaptogen refers to plants proposed to support adaptation to stress. It comes from modern research and is not identical to the Ayurvedic rasayana concept. Health Canada uses it in the Tulsi monograph for specified leaf preparations. The term alone does not establish the efficacy of any tea or extract.
How long can I take Holy Basil?
A reliably safe long-term duration has not been established. Trials in the 2017 review lasted two to thirteen weeks; the stress trials discussed here lasted six and eight weeks. These data establish neither indefinite use nor a particular cycling schedule. Seek professional advice before extended medicinal use or with regular medication.
Which form is most effective: tea, capsule, or extract?
There is no reliable direct comparison of tea, leaf powder and the extracts discussed here. Stress trials tested specific extracts, including whole-plant OciBest, so their results do not automatically apply to tea or arbitrary capsules. These studies also do not establish tea as universally safest. Check the exact preparation and its precautions.
8 sources.
- Saxena RC; Singh R; Kumar P; Negi MPS; Saxena VS; Geetharani P; Allan JJ; Venkateshwarlu K. Efficacy of an Extract of Ocimum tenuiflorum (OciBest) in the Management of General Stress: A Double-Blind, Placebo-Controlled Study. 2012. doi:10.1155/2012/894509
- Lopresti AL; Smith SJ; Metse AP; Drummond PD. A randomized, double-blind, placebo-controlled trial investigating the effects of an Ocimum tenuiflorum (Holy Basil) extract (Holixer™) on stress, mood, and sleep in adults experiencing stress. 2022. doi:10.3389/fnut.2022.965130
- Agrawal P; Rai V; Singh RB. Randomized placebo-controlled, single blind trial of holy basil leaves in patients with noninsulin-dependent diabetes mellitus. 1996. PMID:8880292
- Kelm MA; Nair MG; Strasburg GM; DeWitt DL. Antioxidant and cyclooxygenase inhibitory phenolic compounds from Ocimum sanctum Linn.. 2000. doi:10.1016/S0944-7113(00)80015-X
- Jamshidi N; Cohen MM. The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature. 2017. doi:10.1155/2017/9217567
- Cohen MM. Tulsi - Ocimum sanctum: A herb for all reasons. 2014. doi:10.4103/0975-9476.146554
- Health Canada, Natural and Non-prescription Health Products Directorate. Holy basil – Ocimum tenuiflorum – Leaf. 2026. Source
- Chen SJ; Wang MH; Chen IJ. Antiplatelet and calcium inhibitory properties of eugenol and sodium eugenol acetate. 1996. doi:10.1016/0306-3623(95)02089-6
Legal notice: The depiction of historical significance and traditional use is context within our encyclopedia and not a health claim for any product, not a treatment promise, and not a substitute for medical advice. What may be stated on product labels, product pages, or in advertising is governed by the applicable legal requirements.