What are adaptogens? The herbs, the idea and what trials show
The Soviet idea behind adaptogens, the main adaptogenic herbs from ashwagandha to rhodiola and ginseng, what their trials found, UK rules and safety.
- Written by
- Alex W.
- Last updated
- Reading time
- 9 min read
Overview
Adaptogens are herbs and mushrooms said to help the body cope with stress, such as ashwagandha, rhodiola and Panax ginseng. The term began as a Soviet theory in 1947 and isn't accepted for medicines in the EU. Ashwagandha has moderate evidence for sleep, while stress and fatigue results for most herbs are mixed.
Key points
- A Soviet scientist coined the word adaptogen in 1947 for substances said to raise general resistance to stress.
- European regulators say the idea needs further clarification and don't accept the term for medicines.
- Ashwagandha improved sleep a little in 5 trials, but its effect on how stressed people felt was unclear.
- Rhodiola and Panax ginseng gave mixed fatigue results, and holy basil rests on two small trials.
- Ashwagandha has rare links to liver injury, and several herbs interact with common medicines.
The word adaptogen doesn't come from an ancient herbal. A Soviet scientist, N. V. Lazarev, coined it in 1947 for substances that might raise the body's general resistance to stress [1][2].
Adaptogens are herbs and mushrooms said to help the body cope with stress, such as ashwagandha, rhodiola and Panax ginseng. In plain terms, the label is a theory, not a proven effect. European regulators don't accept the term for medicines [2]. Trial results also differ from herb to herb, so it pays to judge each one on its own.
What are adaptogens?
Lazarev's idea was a substance that made the body hold up better against stress of any kind, not just one. Later, the Soviet researcher Israel Brekhman set out three tests. An adaptogen had to be almost harmless. It had to work on stress in general. And it had to help bring the body back to normal [2].
Brekhman and his colleague Dardymov grouped five plants as adaptogens, Panax ginseng, eleutherococcus, rhaponticum, rhodiola and schisandra [1]. Our history of nootropics guide tells the Soviet story in more detail.
In the UK, the word is also a legal point. The advertising watchdog, the ASA, treats "adaptogenic" as a health claim. It took the word to mean natural substances believed to help the body respond to stress, and no such claim is allowed in ads [3].
What do adaptogens do?
The theory is that an adaptogen softens the body's stress response, so a hard day takes less out of you. Think of it as a shock absorber, not an accelerator. Supporters say this sets it apart from a stimulant. A stimulant lifts how much work you can do for a while, and then you dip [2].
It turns out much of this rests on lab and animal work. In 2008 the European Medicines Agency (EMA) looked at the whole idea. It found the human trials had flaws, such as unclear designs, and some had very few people. Its verdict was that the idea "needs further clarification" [2].
What are the main adaptogenic herbs?
These herbs are often sold as adaptogens. Here's what human trials found for each.
| Herb | What trials found | Evidence |
|---|---|---|
| Ashwagandha, sleep | A small improvement in sleep over placebo in 5 trials of 400 adults [4] | Moderate |
| Ashwagandha, stress | Lower cortisol across 7 trials, but no clear change in how stressed people felt [5] | Mixed |
| Rhodiola rosea | Some fatigue trials positive and others not, across 11 trials at high or unclear risk of bias [6] | Mixed |
| Panax ginseng | Less fatigue than placebo in pooled trials, from reviews rated low quality, and no help with physical performance [7] | Mixed |
| Eleutherococcus (Siberian ginseng) | No clear difference from placebo for long-term fatigue in a trial of 96 adults [8] | Early |
| Holy basil | Lower stress scores than placebo after 6 to 8 weeks in two trials, both using extracts from the same maker [9][10] | Early |
The twist with eleutherococcus is in its name. It's sold as Siberian ginseng, but it isn't one of the Panax plants at all [11]. The EMA accepts it only for traditional use, because flaws in its studies stopped any firm conclusions [12].
Mushrooms such as reishi and cordyceps are often sold as adaptogens too. Our functional mushrooms guide sets out what human trials of each found.
Do adaptogens work?
Here's the tally so far. Ashwagandha has a moderate result for sleep, but its stress results are mixed. Rhodiola and ginseng are mixed too. Holy basil and eleutherococcus rest on a few small trials. You can compare the studies for each herb in our Ingredient Atlas.
Notice what the trials measure. Each one tests a single herb for a single outcome, such as sleep or fatigue, rather than resistance to every kind of stress, which is the adaptogen idea itself.
Some herbs do have a UK licence of sorts. Several rhodiola products and one Panax ginseng product are registered as traditional herbal medicines, for symptoms such as tiredness and exhaustion. That rests on long use, not on trial results. No ashwagandha product holds one [13].
How to choose an adaptogen supplement
Start with the herb, not the word. Pick the one whose trials match what you're after, then check the label for three things.
- The plant part. Root and leaf are not the same. Four of the five ashwagandha sleep trials used a root-only extract [4].
- The extract. Look for a named extract or a stated strength, so you can match it to the trials.
- The daily amount. Compare it with the doses used in the herb's trials, which each herb guide lists.
In plain terms, a blend that lists six herbs in small amounts tells you less than one herb at a tested dose.
Are adaptogens safe?
Each herb has its own safety profile, so it helps to check the one you're considering.
- Ashwagandha. There have been rare cases of liver injury, 25 in published reports, and most people got better after stopping [14]. It's not advised if you have a thyroid or autoimmune condition or before surgery. It may also interact with medicines for diabetes, blood pressure, thyroid or seizures, with sedatives and with medicines that dampen the immune system [15].
- Panax ginseng. Reported side effects include stomach upset, headache and trouble sleeping [7]. The EMA doesn't recommend it for under 18s [16].
- Eleutherococcus. Trouble sleeping, irritability, a fast heartbeat and headaches have been reported, and the EMA says not to use it for more than 2 months [12].
If you're pregnant or breastfeeding, ashwagandha and ginseng are both advised against [15][16]. If you take any regular medicine, check with your GP or pharmacist first.
Where Nooroots fits
If ashwagandha is the herb you're most interested in, Nooroots Ashwagandha + Lion's Mane pairs certified organic KSM-66 ashwagandha with lion's mane fruiting body extract, for calm focus and calm resilience on demanding days. It's caffeine-free.
Frequently asked questions
What does adaptogen mean in simple terms?
It means a herb or mushroom said to help the body handle stress in general. The term comes from Soviet research in the 1940s, and the European Medicines Agency says it isn't accepted in medical terms used in the EU [2].
Is ashwagandha an adaptogen?
It's often sold as one, but it wasn't on the original Soviet list, which named Panax ginseng, eleutherococcus, rhaponticum, rhodiola and schisandra [1].
Can you take adaptogens every day?
Regulators set time limits for some. The EMA says up to 3 months for Panax ginseng and up to 2 months for eleutherococcus [12][16].
What are adaptogenic mushrooms?
They're mushrooms such as reishi and cordyceps that are marketed as adaptogens. Our functional mushrooms guide covers what human trials of each found.
Do adaptogens lower cortisol?
Ashwagandha lowered cortisol, a stress hormone, in pooled trials, but people didn't clearly feel less stressed [5]. One holy basil trial also found lower cortisol in hair, and in saliva after a stress test [9].
What is the difference between adaptogens and nootropics?
Adaptogens are said to help the body handle stress in general, while nootropics are substances people use for memory and focus. Our guide to nootropics explains that term.
Read more about where the adaptogen idea came from in our history of nootropics.
References
Every source here is listed so you can read it yourself. This guide is for general information and doesn't replace advice from your GP. We check it again at least every six months.
- Todorova V, Ivanov K, Delattre C, Nalbantova V, Karcheva-Bahchevanska D, Ivanova S (2021). Plant Adaptogens-History and Future Perspectives. Nutrients 13(8): 2861. PMID 34445021
- European Medicines Agency, Committee on Herbal Medicinal Products (2008). Reflection paper on the adaptogenic concept. EMEA/HMPC/102655/2007. Accessed 31 October 2026. ema.europa.eu
- Advertising Standards Authority. ASA ruling on Minerva Wellness Ltd, A25-1313816. Published 25 March 2026. Accessed 31 October 2026. asa.org.uk
- Cheah KL, Norhayati MN, Husniati Yaacob L, Abdul Rahman R (2021). Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLOS ONE 16(9): e0257843. PMID 34559859
- Albalawi AA (2025). Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress - A systematic review and meta-analysis. Nutrition and Health 31(4): 1395-1408. PMID 40746175
- Ishaque S, Shamseer L, Bukutu C, Vohra S (2012). Rhodiola rosea for physical and mental fatigue: a systematic review. BMC Complementary and Alternative Medicine 12: 70. PMID 22643043
- Li Z, Wang Y, Xu Q, Ma J, Li X, Tian Y et al. (2023). Ginseng and health outcomes: an umbrella review. Frontiers in Pharmacology 14: 1069268. PMID 37465522
- Hartz AJ, Bentler S, Noyes R, Hoehns J, Logemann C, Sinift S et al. (2004). Randomized controlled trial of Siberian ginseng for chronic fatigue. Psychological Medicine 34(1): 51-61. PMID 14971626
- 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(TM)) on stress, mood, and sleep in adults experiencing stress. Frontiers in Nutrition 9: 965130. PMID 36185698
- Saxena RC, Singh R, Kumar P, Negi MP, Saxena VS, Geetharani 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
- Kos G, Czarnek K, Sadok I, Krzyszczak-Turczyn A, Kubica P, Fila K et al. (2025). Eleutherococcus senticosus (Acanthopanax senticosus): An Important Adaptogenic Plant. Molecules 30(12): 2512. PMID 40572479
- European Medicines Agency. Eleutherococci radix (eleutherococcus root), herbal medicine summary for the public. First published 10 February 2016. Accessed 31 October 2026. ema.europa.eu
- Medicines and Healthcare products Regulatory Agency. Herbal medicines granted a traditional herbal registration (THR), list dated 27 October 2025. Accessed 31 October 2026. gov.uk
- McIntyre D, Nguyen P, Kim Y, Meyer B, Salloum M (2026). Ashwagandha (Withania somnifera)-Associated Liver Injury: A Scoping Review of Clinical Characteristics and Safety Considerations. Cureus 18(5): e109764. PMID 42367407
- National Center for Complementary and Integrative Health. Ashwagandha. Last updated March 2023. Accessed 31 October 2026. nccih.nih.gov/health/ashwagandha
- European Medicines Agency, Committee on Herbal Medicinal Products (2024). European Union herbal monograph on Panax ginseng C.A.Mey., radix, Revision 1. EMA/HMPC/27744/2023. Accessed 31 October 2026. ema.europa.eu
