Tulsi (Holy Basil): Plant Profile, Traditional Use, and Modern Research
The 30-second answer
Tulsi, also called holy basil, is the leafy aerial part of Ocimum tenuiflorum – a perennial plant in the Lamiaceae (mint) family. It is one of the most sacred plants in Hindu tradition and one of the most widely used herbs in Ayurveda, classified as a Rasayana and adaptogen. Modern research has investigated its effects on stress, immunity, blood sugar, and inflammation in roughly a dozen small-scale randomised controlled trials. Three medicinal varieties exist: Rama, Krishna, and Vana. As a food supplement in the UK, it is regulated under food law, not as a medicine.
Key facts
- Plant family: Lamiaceae (mint family) – same as basil, mint, and rosemary
- Parts used: leaves and flowering tops; occasionally seeds
- Active compounds: eugenol, ursolic acid, rosmarinic acid, beta-caryophyllene, oleanolic acid
- Varieties: Rama (green), Krishna (purple), Vana (wild forest)
- Traditional context: Rasayana, daily household tonic, sacred plant
- Doses studied: 300mg–2.5g daily, leaf extract or dried leaf, 4–12 weeks
- Should not use: pregnancy, anticoagulant medication, men trying to conceive (theoretical fertility caveat)
What is tulsi?
Tulsi has the unusual distinction of being a plant worshipped daily by hundreds of millions of people. Its botanical name is Ocimum tenuiflorum (formerly classified as Ocimum sanctum), and it is a perennial aromatic shrub native to the Indian subcontinent. The plant grows 30 to 60 centimetres tall, with small purplish or white flowers and oval, slightly serrated leaves that release a sharp, clove-like aroma when crushed.
The Sanskrit name tulsi means “the incomparable one.” In English, the plant is most commonly called holy basil – a name that captures both its religious status in Hindu tradition and its place in the wider basil family. Unlike sweet basil (Ocimum basilicum), tulsi is hotter, sharper, and dramatically higher in eugenol, the aromatic compound also responsible for the smell of cloves.
The leaves are the primary medicinal part.
Which parts of the plant are used?
The leaves and flowering tops are the primary medicinal parts. They contain the highest concentration of essential oils and are used in almost all traditional preparations and clinical research. Leaves are typically harvested before the plant fully flowers, when the essential oil content peaks.
The seeds are used occasionally in traditional digestive formulations but are uncommon in modern supplements. The roots are rarely used medicinally.
The three varieties
Three varieties of tulsi are recognised in Ayurvedic and supplement traditions:
- Rama tulsi – green-leaved, mild aroma, the most widely grown and the variety most often used in commercial tulsi tea.
- Krishna tulsi – purple-tinged leaves, sharper flavour, traditionally considered the most potent and most often associated with religious worship.
- Vana tulsi – wild forest tulsi, hardier and described in Ayurvedic literature as the most adaptogenic of the three.
Most quality supplements use either Rama or Krishna varieties, often blended for a balanced phytochemical profile. Most clinical trials have used Rama or unspecified leaf material; Vana is less frequently studied.
Did you know?
Tulsi is one of the only medicinal plants in the world with continuous religious status. It has been planted in the courtyards of Hindu households for over a thousand years – ostensibly for daily worship, but with the practical effect that every family had immediate access to a fresh medicinal plant.
Active compounds
Tulsi’s aromatic essential oil contains a distinctive blend of compounds that account for most of its phytochemical activity. Eugenol – the dominant aromatic, also found in cloves – typically makes up 40–70% of the essential oil. Beta-caryophyllene contributes a peppery note and binds to certain endocannabinoid receptors. Ursolic acid and oleanolic acid are pentacyclic triterpenoids associated with anti-inflammatory and antioxidant properties in laboratory studies. Rosmarinic acid, the compound also responsible for some of rosemary’s phytochemistry, is present at meaningful levels.
The chemical composition varies between varieties: Krishna tulsi tends to be higher in eugenol; Vana tulsi shows higher levels of methyl chavicol; Rama tulsi sits between the two.
1,500+
years in continuous Hindu household use
3
medicinal varieties
12+
randomised controlled trials
A brief history of tulsi
Tulsi’s history blends religion, medicine, and botany in a way few other herbs can match.
c. 1500 BCE – 600 CE
Vedic and classical Ayurvedic period
Tulsi appears in the Rig Veda, one of the oldest religious texts in the world, where it is praised for its protective and purifying qualities. By the time of the Charaka Samhita (c. 200 BCE – 200 CE), tulsi (referred to as Surasa) was firmly established in the medical canon and listed in formulations for fevers, respiratory complaints, and digestion.
c. 300 – 1000 CE
Religious and household tradition
The Padma Purana and Bhagavata Purana describe tulsi as a goddess and the consort of Vishnu. This sacred status produced one of the longest-running examples of integrated medicine in history: tulsi has been planted in the courtyards of Hindu households for over a thousand years.
c. 600 – 1700 CE
Medieval and Mughal era
The 16th-century Bhavaprakasha dedicated several verses to tulsi, describing its rasa, virya, and clinical applications. Unani-Tibb practitioners adopted it as a cooling and decongestant herb under Mughal patronage.
1700s – 1947
Colonial era
William Roxburgh catalogued tulsi in his Flora Indica (published posthumously in 1832). British colonial physicians – who could hardly miss a plant grown in every Hindu household – documented its use for fevers, coughs, and as an insect repellent. Sir George Watt’s Dictionary of the Economic Products of India (1889–1893) noted its essential oil.
1950s – 1990s
Chemistry and early research
Indian chemists isolated tulsi’s active compounds from the 1950s onward. A landmark 1996 paper by Agrawal et al. in the International Journal of Clinical Pharmacology and Therapeutics was one of the first published RCTs on any Ayurvedic herb, measuring fasting blood glucose in patients with type 2 diabetes.
2000s – present
Modern revival
A widely cited 2014 review by Marc Maurice Cohen in the Journal of Ayurveda and Integrative Medicine – titled “Tulsi: The Mother Medicine of Nature” – pulled together decades of pharmacological evidence and helped popularise the herb in the global wellness market. Tulsi tea brands proliferated in the West.
Traditional Ayurvedic context
In classical Ayurveda, tulsi is described as pungent, bitter, light, and warming. It primarily balances kapha and vata doshas (and can mildly aggravate pitta when overused).
The presence of tulsi in a household is said to bring prosperity, and its leaves are used in daily worship as offerings to the divine.
— traditional Hindu household practice, documented across multiple Puranic texts
Traditional Ayurvedic descriptions of tulsi’s role include use in respiratory contexts (cough, cold, congestion), fever-related formulations, digestive sluggishness, daily rasayana use for resilience, and topical applications for skin and insect bites. These descriptions reflect classical Ayurvedic categorisation and historical use; they do not constitute claims about the effects of any modern food supplement.
Modern research
The clinical evidence base for tulsi is smaller than ashwagandha’s but spans a wider range of conditions. Most trials are small (20–100 participants), Indian-led, and use either dried leaf, leaf extract, or essential oil at varying doses. The studies described below are reported here as published research; the descriptions are not statements about the effects of any r‑veda product.
| Topic | Study | Participants | Duration |
|---|---|---|---|
| Stress | Saxena 2012 | 35 | 6 weeks |
| Anxiety | Bhattacharyya 2008 | 35–39 | 60 days |
| Immune markers | Mondal 2011 | 24 | 4 weeks |
| Blood glucose | Agrawal 1996 | 40 | 4 weeks |
| Blood glucose | Somannavar 2012 | 24 | 8 weeks |
| Metabolic markers | Satapathy 2017 (review) | Multiple trials | – |
| Comprehensive review | Cohen 2014 | Pharmacological synthesis | – |
| Stress / mood (review) | Jamshidi & Cohen 2017 | Multiple trials | – |
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See full study details
Stress and anxiety research
Saxena et al. (2012, Evidence-Based Complementary and Alternative Medicine) ran a six-week RCT in 35 adults with stress-related symptoms. The treatment group received 1,200mg of tulsi leaf extract daily, with perceived stress and sleep parameters as endpoints. Bhattacharyya et al. (2008, Nepal Medical College Journal) studied 35–39 patients with generalised anxiety symptoms over 60 days, measuring scores on the Hamilton Anxiety Rating Scale.
Immune-related research
Mondal et al. (2011, Journal of Ethnopharmacology) ran a four-week double-blind crossover trial in 24 healthy volunteers given 300mg of ethanolic tulsi leaf extract daily. The trial measured changes in interferon-gamma, interleukin-4, and percentages of T-helper and natural killer cells.
Metabolic research
Agrawal et al. (1996) ran one of the earliest tulsi RCTs in 40 patients with type 2 diabetes, measuring fasting and postprandial glucose over four weeks of 2.5g/day dried leaf powder. Somannavar et al. (2012) replicated similar measurements in a smaller trial.
Reviews and syntheses
Cohen’s 2014 review in the Journal of Ayurveda and Integrative Medicine pulled together decades of pharmacological and clinical evidence. Jamshidi and Cohen’s 2017 review in Evidence-Based Complementary and Alternative Medicine pooled the available human evidence on stress and mood endpoints.
How to read this evidence base
Tulsi trials are smaller and more heterogeneous than ashwagandha’s. Most use leaf extract rather than standardised compounds, doses range widely, and dose-response data is thin. Robust human trials in respiratory contexts are limited despite the herb’s deep traditional use in that area. The picture across the evidence base is consistent with a broad-spectrum traditional adaptogen rather than a targeted single-system intervention.
Forms and preparations
Tulsi has historically been consumed in several forms.
- Fresh leaves–chewed or steeped in water; the most traditional household form
- Tulsi tea–dried leaves infused in hot water; the most popular Western form
- Decoction (kadha)–leaves simmered with other warming herbs
- Tincture–alcoholic extract of leaf material
- Capsule–standardised leaf extract; the most dose-accurate option for daily use
Doses used in clinical research range from 300mg of standardised leaf extract daily up to 2.5g of dried leaf powder, typically over study periods of 4 to 12 weeks. These figures describe what has been studied in research – they are not dietary recommendations.
Suitability and cautions
Tulsi is generally well tolerated, but a few cautions apply:
- Pregnant or breastfeeding women should avoid medicinal doses (food-amount tulsi tea is generally considered fine).
- People taking warfarin, aspirin, or other anticoagulants should consult a GP before use, as tulsi may have mild blood-thinning effects.
- Animal studies have raised theoretical concerns about effects on male fertility; men actively trying to conceive may prefer to err on the side of caution.
- People with diabetes on glucose-lowering medication should monitor blood sugar, as tulsi may further lower it.
- People taking sedatives or anti-anxiety medication should consult a GP before use.
As with any food supplement, stop use and consult a healthcare professional if you experience any adverse effects.
