Tulsi

The name Tulasi, the Sanskrit name for Tulsi, is traditionally understood to mean "the incomparable one". In English, it is called holy basil because it is regarded as a sacred plant in India, where it is commonly grown in homes and temples. Tulsi is native to the Indian subcontinent and has been used in Ayurvedic medicine for more than 3,000 years (Jamshidi & Cohen, 2017).

In Ayurveda, Tulsi leaves are traditionally used as a general tonic and as a household herb in teas and decoctions (Jamshidi & Cohen, 2017). It is classified as a herb with pungent (katu) and bitter (tikta) taste, light (laghu) and dry (ruksha) qualities, and heating potency (ushna virya). Its post-digestive effect (vipaka) is pungent (katu). Tulsi is traditionally described as pacifying the Vata and Kapha doshas.

Tulsi is known by the following names in different languages.

• Botanical name: Ocimum tenuiflorum L. 
• English: Holy basil, sacred basil
• Sanskrit: Tulasi, Surasa
• Hindi: Tulsi
• Tamil: Thulasi
• Telugu: Tulasi
• Marathi: Tulas
• Malayalam: Trittavu, Tulasi
• Kannada: Tulasi
• Manipuri: Tulsi
• Angami (Nagaland): Nhietso, Nietso
• Urdu: Raihan, Tulsi

The leaf contains many compounds, and their amounts differ with the type of Tulsi, the growing conditions and the preparation (Jamshidi & Cohen, 2017). The main compounds are listed below.

• Eugenol: a major aromatic compound of the leaf, found in all three types of Tulsi in varying amounts, with antimicrobial activity reported in laboratory studies (Shane-McWhorter, 2025).
• Ursolic acid: a plant triterpenoid present in the leaf
• Rosmarinic acid: a phenolic compound present in the leaf
• β-Caryophyllene: a terpene found in the essential oil of the leaf (Shane-McWhorter, 2025).
• Linalool: a fragrant monoterpene alcohol found in the essential oil of the leaf.
• 1,8-Cineole (eucalyptol): a monoterpene found in the essential oil of the leaf (Jamshidi & Cohen, 2017; Shane-McWhorter, 2025).
• Apigenin: a flavonoid reported in Tulsi leaf.

Laboratory and animal studies have described antioxidant, anti-inflammatory and antimicrobial activity of Tulsi leaf extracts, but these effects have not been adequately confirmed in clinical trials in humans (Jamshidi & Cohen, 2017).

Laboratory, animal and clinical studies have investigated the following potential properties of Tulsi (Jamshidi & Cohen, 2017).

• Adaptogenic: may help the body respond to physical and emotional stress, as suggested by small clinical trials in adults.
• Antioxidant: may help limit oxidative stress in laboratory models.
• Anti-inflammatory: may affect inflammatory markers in laboratory and animal studies.
• Antimicrobial: Tulsi extracts have shown activity against some bacteria, viruses and fungi in laboratory studies, but their effectiveness against infections in humans has not been established.
• Immunomodulatory: may influence immune cell activity in small studies in healthy adults, although evidence in humans is limited.
• Potential antiplatelet effect: may slow blood clotting, which is why caution is needed with blood thinners (Shane-McWhorter, 2025).

Most of these properties have been observed mainly in laboratory and animal research, which cannot confirm the same effects in people. Human evidence comes from small, short studies of different Tulsi products, and many studies have limitations in quality (Jamshidi & Cohen, 2017). Tulsi is not a substitute for medical treatment or prescribed medicines.

Three types of Tulsi are commonly described. Two are cultivars of Ocimum tenuiflorum, while the third is a separate species (Jamshidi & Cohen, 2017).

• Rama tulsi (Sri tulsi): a cultivar of Ocimum tenuiflorum with green leaves.
• Krishna tulsi (Shyama tulsi): a cultivar of Ocimum tenuiflorum with purplish leaves. The two cultivars differ in their botanical and chemical features (Jamshidi & Cohen, 2017).
• Vana tulsi: the wild or forest Tulsi, which is a separate species, Ocimum gratissimum, with dark green leaves. It is traditionally used similarly to the other two types (Jamshidi & Cohen, 2017).

Most clinical studies have not specified which type was used, so the effects of one type cannot be reliably compared with another (Jamshidi & Cohen, 2017).

Tulsi has been studied for its potential effects on stress management, immune function, inflammation and glucose metabolism. It is also traditionally used to support respiratory and digestive comfort and in skin, scalp and oral-care practices. However, evidence varies across these uses, and many proposed benefits have not been confirmed in human studies.

1. May Support Normal Immune Function

Tulsi contains bioactive compounds, including eugenol and rosmarinic acid, that have been studied for their antioxidant and immunomodulatory properties. These compounds may influence oxidative stress and immune signalling, which are involved in the body's normal defence mechanisms. However, much of the evidence comes from laboratory and animal studies, and human research has not established that Tulsi boosts immune cell activity or prevents infections.

2. May Help the Body Respond to Stress

Tulsi is traditionally regarded as an adaptogen in Ayurveda, meaning it is used to support the body's response to physical and emotional stress. A clinical trial of a standardised Tulsi extract reported improvements in perceived stress, sleep scores and certain cortisol measures over eight weeks (Lopresti et al., 2022). These findings suggest a possible role in supporting stress responses, but further research is needed to confirm the effects of different Tulsi preparations. It has not been established as a treatment for anxiety or other mental health conditions.

3. Traditionally Used for Respiratory Comfort

Tulsi is traditionally included in preparations used for respiratory comfort. Compounds such as eugenol have demonstrated anti-inflammatory and antimicrobial activity in preclinical research, which may help explain the interest in its traditional respiratory uses. However, these findings do not establish that Tulsi clears blocked airways, eases breathing or treats respiratory conditions in humans. It should not replace prescribed respiratory medicines or medical assessment.

4. Traditionally Used to Support Digestion

Tulsi has a traditional role in supporting digestion. Experimental research has investigated its extracts for possible effects on gastrointestinal inflammation and digestive processes. However, there is insufficient human evidence to establish that Tulsi stimulates digestive enzyme production, improves nutrient absorption, regulates gut microbiota or consistently relieves gas and bloating.

5. Contains Compounds Studied for Anti-inflammatory Activity

Tulsi contains compounds such as eugenol and ursolic acid that have been investigated for their effects on inflammatory pathways. Preclinical studies suggest that some of these compounds may influence the biological processes involved in inflammation. However, these findings do not establish that Tulsi relieves chronic pain, treats inflammatory conditions or reduces the risk of inflammatory disorders in humans.

6. Shows Antimicrobial Activity in Laboratory Studies

Tulsi extracts and essential oils have shown activity against certain bacteria, fungi and other microorganisms in laboratory studies. Its bioactive compounds may interfere with microbial growth or other cellular processes, depending on the preparation and concentration studied. However, laboratory findings do not establish that consuming Tulsi prevents or treats infections in humans, and further clinical research is needed.

7. Has Been Studied for Its Potential Effects on Liver Health

Experimental research has investigated whether Tulsi extracts influence oxidative stress and fat accumulation in liver tissue. Some animal studies suggest that its compounds may affect antioxidant enzymes and biological processes associated with liver injury and fat metabolism. However, these findings do not establish that Tulsi water detoxifies the liver, prevents liver damage or benefits people with fatty liver disease. Human evidence remains insufficient to support these effects.

8. May Influence Glucose Metabolism

Preliminary experimental and clinical research has investigated whether Tulsi affects blood glucose, insulin levels and insulin sensitivity. These possible effects may involve changes in glucose metabolism and the body's response to insulin. However, the available evidence is limited and does not establish that Tulsi controls diabetes or prevents its complications. It should not be used as a substitute for prescribed diabetes medicines.

9. Has Been Studied for Skin and Scalp Health

Tulsi's antioxidant and antimicrobial properties have been investigated for their possible relevance to skin and scalp health. These properties provide a basis for studying its traditional topical uses. However, clinical evidence is insufficient to establish that Tulsi treats acne, dandruff or hair loss, strengthens hair roots or improves hair growth. Claims that it detoxifies the skin are also not established by clinical evidence.

10. May Support Oral Hygiene

Tulsi extracts have demonstrated activity against certain oral bacteria in laboratory research. This has prompted interest in their potential role in oral hygiene, particularly in relation to microbial growth in the mouth. However, human evidence is insufficient to establish that Tulsi prevents tooth decay, gum disease or bad breath. It should be considered distinct from established oral hygiene practices, including brushing with fluoride toothpaste and regular dental care.

Tulsi is used in the following ways. These uses reflect traditional and household practices and should not be considered proven medical treatments (Jamshidi & Cohen, 2017).

Role in Ayurvedic Practice

In Ayurveda, Tulsi leaves are traditionally used as a general tonic and as an ingredient in herbal preparations, often with other herbs. These uses are based on traditional practice, and most have not been evaluated in clinical trials (Jamshidi & Cohen, 2017).

Household Use in Food and Drink

Fresh or dried leaves are added to herbal teas and traditional decoctions for their aroma and taste. This household use does not necessarily provide the doses studied in clinical trials.

Cultural and Spiritual Use

Tulsi is regarded as a sacred plant in Indian households and is grown in homes and temples. It is used in daily worship and religious ceremonies, and this cultural practice is not a medical use.

Not everyone can use Tulsi safely. The groups and situations below should seek medical advice before use.

Pregnancy and Trying to Conceive

Avoid medicinal amounts of Tulsi during pregnancy. In animal studies, large doses were associated with reduced implantation of fertilised eggs and a lower likelihood of pregnancy continuing to full term. It is not known whether these effects occur in humans, and anyone trying to conceive is advised to avoid medicinal use (Shane-McWhorter, 2025).

Breastfeeding

The safety of Tulsi during breastfeeding has not been studied (Shane-McWhorter, 2025). A breastfeeding mother should consult her doctor before using it in medicinal amounts.

Children and Teenagers

A safe dose of Tulsi for children and teenagers has not been established. Use it in this age group only if advised by a paediatrician or a qualified Ayurvedic physician.

Bleeding Disorders and Planned Surgery

Laboratory and animal evidence suggests that Tulsi may inhibit platelet aggregation and affect blood clotting, potentially increasing the risk of bleeding during and after surgery (Shane-McWhorter, 2025). People with a bleeding disorder, and those who are due to undergo surgery or a dental procedure, should consult their doctor and tell the surgeon about Tulsi use. 

Diabetes

Blood glucose may fall with Tulsi use. One clinical trial found that adding Tulsi to a diabetes medicine was associated with a greater reduction in blood glucose than the medicine alone (Jamshidi & Cohen, 2017). People with diabetes should monitor blood glucose and consult their doctor before use.

Thyroid Disease

Levels of the thyroid hormone thyroxine may decrease with Tulsi use, which could worsen an underactive thyroid (Shane-McWhorter, 2025). Anyone with a thyroid disorder, or who takes thyroid medicine, should use it only on medical advice. 

Allergy

Allergic reactions such as skin rash or itching can occur with herbal products. Stop using Tulsi if these symptoms appear. Seek emergency care for swelling of the face or lips or difficulty breathing.

Long-Term Use

Available evidence suggests that use for up to 8 weeks may be safe for most people, but use beyond 8 weeks has not been studied (Shane-McWhorter, 2025). Consult a doctor before using it for longer. 

Tulsi is available as leaves, powder, capsules, tablets and tincture. Use only the form and amount advised by your doctor or Ayurvedic physician. The steps for each form are given below.

Preparing Tulsi Tea

• Place 1 to 2 teaspoons of dried Tulsi leaves, or 5 to 10 fresh leaves, in a cup.
• Pour about 200 mL of freshly boiled water over the leaves.
• Cover the cup and let the leaves steep for 5 to 10 minutes.
• Strain the tea and drink it warm.

Taking Dried Leaf Powder

Use only the amount recommended by your doctor or Ayurvedic physician, as a standard dose has not been established.

• Mix the powder into a glass of warm water.
• Drink the mixture straight away.

Keep to the advised amount, and stop use if any warning symptom described under Side Effects occurs.

Swallowing Capsules or Tablets

• Read the label to check the botanical name, the plant part used and the amount of extract in each capsule or tablet.
• Swallow the capsule or tablet whole with water.
• Take the product at about the same time each day, and follow the dosage instructions on the label or those given by your healthcare professional.
• Discuss use beyond 8 weeks with a doctor, because longer-term use has not been studied (Shane-McWhorter, 2025).

Measuring Tincture Drops

• Read the label to find the number of drops advised and the strength of the tincture.
• Measure the drops with the dropper supplied.
• Dilute the drops in a glass of water and drink the mixture if directed by the product instructions.
• Never exceed the recommended dose.

Herbs Traditionally Used With Tulsi

Tulsi is traditionally combined with the following herbs, often in a decoction (kadha) (Ministry of AYUSH, 2020). 

An official dose of Tulsi has not been established. The amounts below reflect common household use and doses investigated in clinical studies in adults. They should not be treated as recommended doses, as the preparations and study durations varied (Jamshidi & Cohen, 2017).

Children

The safe dose of Tulsi for children has not been established. Give Tulsi to a child only if a paediatrician or a qualified Ayurvedic physician advises, and follow the dose they prescribe.

Teenagers

Dose guidance specific to teenagers is not available. A teenager should use Tulsi only on the advice of a doctor or a qualified Ayurvedic physician.

Adults

• Tea: 1 to 2 cups daily, each prepared with 1 to 2 teaspoons of dried leaves. This reflects common household practice, and no clinical study has tested a specific tea dose.
• Dried leaf powder: 1 to 3 g daily. However, this range should not be considered a clinically established dose. Consult a doctor or qualified Ayurvedic physician for appropriate guidance.
• Leaf extract in capsules or tablets: Clinical studies have used varying doses and preparations, including 300 to 3,000 mg daily for aqueous leaf extracts and 300 to 1,000 mg daily for ethanolic leaf extracts.

Older Adults

Dose guidance for older adults is also not available. Many older adults take regular medicines that can interact with Tulsi, so medical advice is particularly important before use (Shane-McWhorter, 2025). 

Side effects of Tulsi were generally mild in clinical studies, although safety data remain limited (Jamshidi & Cohen, 2017). 

Digestive Upset

Nausea and diarrhoea have been reported (Shane-McWhorter, 2025). In one trial, occasional mild nausea occurred with a 250 mg capsule taken twice daily (Jamshidi & Cohen, 2017). 

Allergic Reactions

Skin rash, itching or swelling may occur in people who are sensitive to Tulsi or related plants in the mint family. Stop use if these symptoms appear.

Bleeding and Bruising

Tulsi may slow blood clotting, which may increase the risk of easy bruising or bleeding, particularly when it is taken with blood thinners (Shane-McWhorter, 2025). 

Low Blood Glucose

Blood glucose may fall with Tulsi use. In people who take diabetes medicines, this may cause hypoglycaemia, with signs such as shakiness, sweating, hunger and confusion (Jamshidi & Cohen, 2017). 

Changes in Thyroid Hormone Levels

Thyroxine levels may decrease with Tulsi use, based on limited evidence, potentially worsening an underactive thyroid (Shane-McWhorter, 2025). 

When to Seek Medical Help

Stop using Tulsi and contact a doctor if unusual bleeding or bruising, black or bloody stools, severe or persistent vomiting or diarrhoea, or signs of low blood glucose occur. Seek emergency care for swelling of the face or lips or difficulty breathing.

Tulsi may affect how some medicines work. The potential interactions are described below, and the doctor should be told about any herbal product in use (Shane-McWhorter, 2025). 

Blood Thinners and Antiplatelet Medicines

Because Tulsi may slow blood clotting, taking it with anticoagulant or antiplatelet medicines may increase the risk of bleeding (Shane-McWhorter, 2025). The doctor should advise on monitoring. 

Diabetes Medicines

In a clinical trial, taking Tulsi alongside a diabetes medicine was associated with a greater fall in blood glucose than the medicine alone (Jamshidi & Cohen, 2017). This may increase the risk of hypoglycaemia, so blood glucose should be monitored. 

Thyroid Medicines

Tulsi may reduce the effectiveness of thyroid hormone medicines (Shane-McWhorter, 2025). People taking these medicines should consult their doctor before using Tulsi and have their thyroid function monitored as advised. 

Sedative Medicines

Animal studies suggest that Tulsi may increase the sedating effect of barbiturates (Shane-McWhorter, 2025). It is not known whether the same occurs in humans or with other sedative medicines, so avoid combining them without medical advice. 

Blood Pressure Medicines

Several small trials have reported changes in blood pressure with Tulsi (Jamshidi & Cohen, 2017). However, a direct interaction with blood pressure medicines has not been established. Consult your doctor before combining them and monitor your blood pressure as advised. 

 Storage of Tulsi

Proper storage helps maintain the quality and safety of Tulsi products. The points below apply to leaves, powder, capsules, tablets and tincture.

• Store in a tightly closed container in a cool, dry place away from direct sunlight.
• Keep fresh leaves in a cool place and use them while they are fresh.
• Do not use any product after its expiry date, and discard dried leaves or powder that smell musty or show mould.
• Keep all products out of the reach of children.
• Follow the storage instructions printed on the label of any supplement.

• Tulsi (holy basil) is a sacred herb in India that has been used in Ayurveda for more than 3,000 years, mainly as a general tonic and a household herb (Jamshidi & Cohen, 2017).
• Small clinical trials suggest that Tulsi leaf extracts may help with stress management and influence immune cell activity, but the evidence remains limited due to the small size and short duration of the studies (Jamshidi & Cohen, 2017; Lopresti et al., 2022).
• Tulsi may affect blood clotting, lower blood glucose and influence thyroid hormone levels. Interactions with blood thinners, diabetes medicines and thyroid medicines are therefore possible (Shane-McWhorter, 2025).
• Avoid medicinal amounts during pregnancy and when trying to conceive, and consult a doctor before prolonged use, as the safety of long-term use has not been established (Shane-McWhorter, 2025).
• Tulsi is not a treatment or cure for any disease. Consult a doctor before using it, especially if you have a medical condition or take regular medicines.