Ocimum sanctum, or holy basil, has been used for thousands of years and is considered a sacred herb in many parts of the world, hence, its name.1 Often dubbed ‘the elixir of life’ and ‘the queen of herbs,’ the uses of holy basil range from an anti-inflammatory, to an expectorant, to a tonic for energy and memory enhancement.2 The plant is typically found in the tropics and subtropical areas, often in homes to be used in religious ceremonies.2 The essential oils of the leaves are very aromatic and contain a wide array of important metabolites.


Believed to have first been grown in the wild in northern India, holy basil reaches a height of almost two feet and has many branches, making it almost seem like a shrub.3 The branches have hairy stems that bear leaves of approximately two inches long that are dark green to almost purple with a pungent scent. When holy basil flowers, the tiny lavender blooms are tightly displayed on a linear spire.

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One of the most important claims of holy basil is as an immune booster. In a double-blind trial of healthy volunteers, participants were given standardized capsules of ethanolic extracts of basil leaves or placebo.1 In the 4-week, post-study phase, participants’ blood samples were analyzed for the content of Th1 and Th2 cytokines (interferon-gamma and interleukin-4) and the results were compared to baseline data. The results showed statistically significant increases in the levels of these two potent immune mediators over baseline in the basil group, when compared to baseline and the placebo group.1

Since the rapidly expanding problem of antimicrobial resistance is being felt worldwide, researchers are constantly searching for alternate compounds with bactericidal action. One study examined the action of Ocimum essential oil on three major pathogens: Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus), Escherichia coli, and Pseudomonas aeruginosa.4 Using oil concentrations of 2.25% and 4%, complete growth inhibition of S aureus and E coli was achieved and partial inhibitory action was seen in P aeruginosa. It should be noted, however, that while these results are impressive, the study only showed bacteriostatic activity and not bactericidal action.

Another feature of holy basil is its apparent modulatory effects on the clinical aspects of metabolic syndrome.5 Researchers in this study recruited 100 volunteers with known elevations in blood glucose, lipids, and blood pressure. The participants were randomly assigned to take either placebo or holy basil extract twice daily for three months. Compared to baseline and the placebo group, the holy basil group showed impressively significant reductions in blood sugar levels, lipid profiles, and blood pressure. The mechanism of action of holy basil on these parameters is believed to be largely due to the herb’s potent anti-inflammatory effect.

Holy basil’s protective action is due, in part, to its free radical scavenging effect. This also reduces oxidative cellular and chromosomal damage from radiation.6 These actions ultimately help reduce end-organ damage and improve post-radiation recovery. Limited clinical studies have shown promise with being able to deliver higher doses of therapeutic radiation in patients taking holy basil without increasing the unwanted side effects of the radiation.6 The protective mechanisms are thought to be due to the increase in antioxidant activity, alteration in gene expression, induction of apoptosis, and the inhibition of angiogenesis and metastasis.7 A substantial part of this protective action is due to enhancement of the liver enzyme systems that detoxify and cleanse the bloodstream of damaging substances.

Safety, interactions, side effects

Holy basil is not recommended for pregnant or nursing mothers or young children. It should also be used with caution in patients with diabetes due to its potential for inducing hypoglycemia.6 Allergic reactions are always a concern with any compound. Persons with allergic histories should be cautious with first-time use of holy basil.

How supplied, dose, cost 

Holy basil is usually found as either chopped and dried leaves, tea, or tincture. Essential oil of holy basil is also becoming very popular. Holy basil products cost from $15 to $45, depending on the quantity and concentration. Also, ‘growing your own’ is becoming increasingly attractive and a packet of several hundred non-GMO seeds can be purchased for as little as $4. Dried leaves are usually dosed by steeping one-half teaspoon in hot water to make a tea and consuming two to three times daily.6


As with all homeopathic remedies, there are many pros and cons. There does not appear to be a substantial downside to the use of holy basil. However, there are still many holes in the research before healthcare providers can safely recommend its use. The concern always exists, especially in cases of cancer and other life-threatening diseases, that patients could unknowingly rely too heavily on this remedy and possibly feel that it could replace traditional therapy. As long as healthcare providers thoroughly educate their patients as to the adjunctive place of holy basil in a treatment regimen, cautious use seems both safe and likely beneficial.


  1. Mondal S, Varma S, Bamola VD, et al. Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on health volunteers. J Ethnopharmacol. 2011;136:452-456.
  2. Cohen MM. Tulsi-Ocimum sanctum: A herb for all reasons. J Ayurveda Integr Med. 2014;5:251-259.
  3. Renter E. Holy basil benefits: Growing your own medicine. Available at http://naturalsociety.com/holy-basil-benefits-growing-your-own-medicine. Posted March 7, 2013. Accessed January 10, 2017.
  4. Yamani HA, Pang EC, Mantri N, Deighton MA. Antimicrobial activity of Tulsi (Ocimum tenuiflorum) Essential Oil and their major constituents against three species of bacteria. Front Microbiol. 2016;7:681.
  5. Devra DK, Mathur KC, Agrawal RP, Bhadu I, Goyal S, Agarwal V. Effect of Tulsi (Ocimum sanctum Linn.) on clinical and biochemical parameters of metabolic syndrome. Journal of Natural Remedies. 2012;12: 63-67.
  6. Tulsi (Ocimum sanctum) as radioprotector in head and neck cancer patients undergoing radiation therapy. Biomedicine. 2012; 32:39-44.
  7. Baliga MS, Rao S, Rai MP, D’Souza P. Radioprotective effects of the Ayurvedic medicinal plant Ocimum sanctum Linn. (holy basil): A memoir. J Cancer Res Ther. 2016;12:20-27.
  8. Skidmore-Roth L. Mosby’s Handbook of Herbs & Natural Supplements. 3rd ed. St. Louis, MO: Elsevier Mosby; 2006.