Holy basil (tulsi), tea or supplement, and how it compares with ashwagandha
What holy basil is, what the trials found on stress and cortisol, tea or capsules, how it compares with ashwagandha and who should check first.
- Written by
- Alex W.
- Last updated
- Reading time
- 8 min read
Overview
Holy basil, or tulsi, is a leafy herb from Ayurvedic medicine, taken as tea or capsules. Two placebo-controlled trials in stressed adults found lower stress scores after 6 to 8 weeks of an extract. Ashwagandha has more trials behind it. Holy basil seems safe short term, but check first if pregnant, trying to conceive, or on thyroid or blood-thinning medicines.
Key points
- Holy basil, or tulsi, is a leafy herb used in Ayurvedic medicine for more than 3,000 years.
- Two placebo-controlled trials in stressed adults found lower stress scores after 6 to 8 weeks.
- One trial found lower cortisol in hair and saliva on holy basil than on a placebo.
- Ashwagandha has more stress trials, and we found no trial comparing the two directly.
- Check with your GP first if you're pregnant, trying to conceive or take thyroid, blood-thinning or diabetes medicines.
What is holy basil (tulsi)?
There isn't just one holy basil. Tradition describes three types of tulsi, one with green leaves, one with purple leaves and a wild forest type, and all three are used in the same way [1].
Holy basil (Ocimum tenuiflorum, also called Ocimum sanctum) is a leafy plant native to the Indian subcontinent, and tulsi is its Hindi name. It has been part of Ayurvedic medicine for more than 3,000 years, where it's often called the "elixir of life" [1].
It's a close relative of the sweet basil used in cooking, but a different plant [2]. Today you'll find it as tulsi tea, powdered leaf and capsules of leaf extract.
What is holy basil good for?
Holy basil is sold as an adaptogen, a plant thought to help the body cope with stress [2]. Stress is also where the strongest trials in people have looked.
A 2017 systematic review found 24 studies of tulsi taken by mouth, with 1,111 people in total. They looked at blood sugar and cholesterol, immunity, and mood and thinking, and all of them reported favourable results [1]. Our page of holy basil studies lists the trials in people, with their doses and lengths.
The reviewers also set out the limits. Only 8 of the 24 studies used a placebo, 3 were rated high quality, and almost all were run in India [1]. So far, that's a positive picture built mostly on small studies.
Does holy basil help with stress?
Two placebo-controlled trials in stressed adults found that it did, at quite different amounts.
In an 8-week trial in Australia, 100 stressed adults with poor sleep took 250 mg a day of a leaf extract or a placebo. Stress scores fell by 37% on holy basil and by 19% on the placebo [3]. The company that makes the extract funded the trial [3].
In an earlier 6-week trial in India, 150 adults with stress symptoms took 1,200 mg a day of a whole-plant extract or a placebo. By week 6, total symptom scores had fallen more on holy basil, including forgetfulness, exhaustion and sleep problems. The two groups were level at weeks 2 and 4 [4].
| Trial | Daily amount and length | What was found |
|---|---|---|
| Lopresti 2022, 100 stressed adults | 250 mg leaf extract for 8 weeks | Stress scores down 37%, against 19% on placebo [3] |
| Saxena 2012, 150 adults with stress symptoms | 1,200 mg whole-plant extract for 6 weeks | Symptom scores fell more than on placebo by week 6 [4] |
Two trials pointing the same way is a promising start, and larger independent trials would make the picture clearer.
Does holy basil lower cortisol?
One trial suggests it may. In the 250 mg trial, people on holy basil had lower cortisol in their hair after 8 weeks than people on the placebo. Their saliva cortisol was also lower around a lab stress test, which involved a hand in cold water and mental arithmetic [3].
The hair test compared the two groups at week 8, rather than tracking each person's change from the start [3]. So it's an early sign from one trial.
Holy basil tea or supplement?
The two stress trials used capsules of concentrated extract, at 250 mg and 1,200 mg a day [3][4]. Across the wider research, doses ran from 300 mg to 3 g of leaf extract, taken one to three times a day, and some studies used fresh leaves or brews of the whole plant [1].
We found no trial that tested tulsi tea for stress. A cup of tea is an easy way to enjoy the plant, while an extract is closer to what the stress trials used. Whichever you choose, follow the amount on the label.
How does holy basil compare with ashwagandha?
Both come from Ayurveda and both are taken for stress, but ashwagandha has more trials behind it. Ashwagandha is widely used as a standardised root extract, while holy basil is mostly taken as its leaves [1][5].
A review of 12 trials with 1,002 adults found that ashwagandha lowered stress scores more than a placebo, though the reviewers rated the certainty of that evidence as low [6]. For holy basil, the stress evidence rests on a few trials, two of them placebo-controlled [1][3][4].
We found no trial that compared the two head to head. One 60-day trial tested a blend that held both, along with rhodiola and other herbs, and stress scores fell further than on a placebo [7]. Because it was a blend, it can't tell you which herb did what. Our guide to ashwagandha covers its trials in detail, and our rhodiola guide compares rhodiola with ashwagandha.
Is holy basil safe?
For most adults it seems safe in the short term. The MSD Manual says it appears safe for up to 8 weeks, and the 2017 review found no serious side effects in studies that lasted up to 13 weeks [1][2]. In the 250 mg trial, side effects such as stomach upset and headache were about as common on the placebo [3].
Nausea and diarrhoea are possible [2]. It's worth checking with your GP or pharmacist first in these cases.
- You're pregnant, breastfeeding or trying to conceive. In animal studies, large doses made a pregnancy less likely to continue, and its safety while breastfeeding hasn't been studied [2].
- You take thyroid medicine. Holy basil might lower thyroxine levels and make thyroid tablets work less well [2].
- You take blood thinners or have surgery coming up. It appears to slow blood clotting, which could raise the risk of bleeding [2].
- You take medicine for diabetes. Several small studies found tulsi lowered blood sugar [1].
Frequently asked questions
Is holy basil the same as tulsi?
Yes. Tulsi is the Hindi name for holy basil, Ocimum tenuiflorum, which is also called Ocimum sanctum [1].
Is holy basil the same as basil?
No. Holy basil is a close relative of the sweet basil used in cooking, but it's a different plant with its own traditional uses [2].
Can holy basil help you sleep?
In one 8-week trial of 250 mg extract, stressed adults rated their sleep better on an insomnia scale than people on a placebo. A wrist sleep tracker found no difference between the groups [3].
Can you take holy basil every day?
Studies have given it every day for up to 13 weeks with few side effects. Less is known about longer use, so follow the amount on the label [1][2].
Can you take holy basil and ashwagandha together?
We found no trial of the two together on their own. One 60-day trial of a blend that held both, with other herbs, reported no side effects linked to it [7]. Ask your pharmacist first if you take regular medicines.
How long does holy basil take to work?
In the two placebo-controlled stress trials, differences from the placebo showed after about 6 weeks of daily use [3][4].
Read more in our guide to L-theanine, another ingredient taken for calm.
References
Every study here is listed so you can read it yourself. This guide is for general information and doesn't replace advice from your GP or pharmacist. We check it again at least every six months.
- Jamshidi N, Cohen MM (2017). The clinical efficacy and safety of tulsi in humans: a systematic review of the literature. Evidence-Based Complementary and Alternative Medicine 2017: 9217567. PMID 28400848
- MSD Manual Professional Version (2025). Holy basil. Merck & Co. msdmanuals.com
- Lopresti AL, Smith SJ, Metse AP, Drummond PD (2022). 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. Frontiers in Nutrition 9: 965130. PMID 36185698
- Saxena RC, Singh R, Kumar P, et al. (2012). Efficacy of an extract of Ocimum tenuiflorum (OciBest) in the management of general stress: a double-blind, placebo-controlled study. Evidence-Based Complementary and Alternative Medicine 2012: 894509. PMID 21977056
- Coope OC, Willems MET, Levington A, et al. (2026). Back to the roots: safety and tolerability of standardised ashwagandha (Withania somnifera) root extract in healthy adults. A systematic review of biomarkers and adverse events. Pharmaceuticals 19(5): 725. PMID 42198398
- Akhgarjand C, Asoudeh F, Bagheri A, et al. (2022). Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials. Phytotherapy Research 36(11): 4115–4124. PMID 36017529
- McKinney E, Stewart J, Kewalramani R, Singh S (2026). Effects of multi-herb and ashwagandha root formulas on stress modulation: a randomized, double-blind, placebo-controlled clinical study. Trials 27(1). PMID 41656269
