Ecdysterone Side Effects: What the Evidence Says
Ecdysterone, a plant steroid found in spinach, quinoa and several traditional herbs, is marketed as a "natural anabolic". A widely discussed 2019 study sparked new interest, and the World Anti-Doping Agency has since placed it on its monitoring list. But what do we actually know about its side effects? Our editorial team reviewed the evidence.
What ecdysterone is
Ecdysterone (20-hydroxyecdysone, also called beta-ecdysone) belongs to the ecdysteroids, a family of steroid hormones that control moulting in insects. Plants produce similar compounds, probably as a defence against insects, and these phytoecdysteroids are found in spinach, quinoa, Cyanotis vaga, Rhaponticum carthamoides (maral root) and Ajuga species.
Despite the steroid backbone, ecdysterone is structurally quite different from testosterone and does not appear to bind the androgen receptor. Laboratory work by Parr and colleagues suggested that its muscle effects in cell and animal models may be mediated partly through oestrogen receptor beta.
Commercial supplements usually contain extracts standardised to a stated percentage of ecdysterone, most commonly from Cyanotis vaga. The amounts on labels range from tens to several hundred milligrams per serving.
In the UK, ecdysterone products are sold as food supplements. The regulatory status of concentrated plant extracts can be complex under novel food rules, and enforcement varies, so availability does not by itself mean a product has been formally assessed for safety.
What human studies have found
Human data are surprisingly scarce for a compound so heavily marketed. An early trial by Wilborn and colleagues in 2006 found no meaningful effect of 200 mg ecdysterone daily on body composition or strength in trained men, although the study was small.
The study that changed the conversation was published in Archives of Toxicology in 2019 by Isenmann and colleagues. Young men in a ten-week resistance programme who took ecdysterone-containing supplements gained more muscle mass and bench press performance than the placebo group.
That trial had important limitations: a small sample, short duration and products whose real content had to be verified. Nevertheless, its results prompted WADA to add ecdysterone to its Monitoring Program, which tracks substances that might be misused but are not prohibited.
Since then, a few further studies have appeared with mixed findings. The overall position is that ecdysterone may have some anabolic potential, but the evidence base is thin, inconsistent and far from settled.
Reported side effects
In the published human trials, no serious adverse effects were reported. The 2019 study measured liver and kidney markers and found no signs of toxicity during the ten-week period. Animal studies have generally shown low acute toxicity even at high doses.
That reassurance comes with caveats. The total number of people studied is small, follow-up periods are short, and rare or long-term effects could easily go undetected. Absence of evidence of harm is not the same as evidence of safety.
- mild digestive discomfort, reported anecdotally by users;
- headache or restlessness, mostly in multi-ingredient products where other components may be responsible;
- theoretical hormonal effects related to oestrogen receptor activity, not confirmed in humans;
- possible effects on blood glucose, suggested by animal studies, which matters for people on diabetes medication.
Because ecdysterone is not an androgen, typical anabolic steroid side effects such as suppression of natural testosterone, acne or hair loss are not expected. However, products sold as "ecdysterone" have been found to contain other undeclared substances, which could produce such effects.
If you choose to use ecdysterone despite these uncertainties, keep a simple record of how you feel and consider asking your GP about routine blood tests, including liver and kidney function, if you plan to use it for longer than a few weeks.
The labelling and contamination problem
Arguably the biggest practical risk is not ecdysterone itself but what is actually in the tub. Analyses by Ambrosio and colleagues found that many ecdysterone supplements contained considerably less, and in some cases far more, than the stated amount.
| Issue | Why it matters | How to reduce the risk |
|---|---|---|
| Under-dosed products | No effect, wasted money | Choose brands with published certificates of analysis |
| Over-dosed products | Unknown exposure beyond studied amounts | Avoid unusually cheap or vague labels |
| Undeclared steroids or SARMs | Health risks and positive doping tests | Use batch-tested products if you compete |
| Proprietary blends | Real dose of each ingredient hidden | Prefer single-ingredient products |
Contamination with prohibited substances is a well-documented problem across the "muscle-building" supplement category. Products marketed as natural anabolics have repeatedly been found to contain anabolic steroids or SARMs, sometimes in pharmacologically active amounts.
For athletes subject to testing, this is a serious concern. Strict liability means a positive test counts regardless of intent. Independent batch-testing schemes reduce, but cannot completely remove, this risk.
Note also that ecdysterone's place on the WADA Monitoring Program means its status could change. Competitive athletes should check the current Prohibited List and UK Anti-Doping guidance before using it.
Who should avoid ecdysterone
Given the limited data, certain groups should not use ecdysterone without medical advice. Pregnant and breastfeeding women, children and adolescents fall into this category, as there is no information on safety in these populations.
People with hormone-sensitive conditions, including some breast and gynaecological cancers, should be cautious because of the possible interaction with oestrogen receptors, even though the clinical relevance in humans is unknown.
Those taking medicines for diabetes should discuss it with their doctor, because of the animal data hinting at effects on glucose metabolism. The same applies to people with liver or kidney disease, simply because they were excluded from trials.
Finally, if you experience unexpected symptoms such as jaundice, dark urine, severe fatigue, mood changes or signs of hormonal disturbance while using any "anabolic" supplement, stop it and seek medical advice. Bring the product with you, as testing it can be informative.
Conclusions of the editorial team
Ecdysterone has a plausible mechanism and one well-known positive human study, but the overall evidence is limited and inconsistent. It is far from proven as a reliable muscle-building aid.
No serious side effects have been documented in short human trials, yet the small number of participants means long-term safety is essentially unknown.
The most concrete risks are poor labelling and contamination with undeclared substances. For tested athletes, the WADA monitoring status adds a further reason for caution.
If this topic interests you, our editorial team has also written about turkesterone, how to judge supplement quality and third-party testing, and the evidence behind creatine for muscle growth.
References
- Isenmann E, Ambrosio G, Joseph JF, et al. Ecdysteroids as non-conventional anabolic agent: performance enhancement by ecdysterone supplementation in humans. Arch Toxicol. 2019;93(7):1807–1816.
- Parr MK, Zhao P, Haupt O, et al. Estrogen receptor beta is involved in skeletal muscle hypertrophy induced by the phytoecdysteroid ecdysterone. Mol Nutr Food Res. 2014;58(9):1861–1872.
- Wilborn CD, Taylor LW, Campbell BI, et al. Effects of methoxyisoflavone, ecdysterone, and sulfo-polysaccharide supplementation on training adaptations in resistance-trained males. J Int Soc Sports Nutr. 2006;3(2):19–27.
- Dinan L, Lafont R. Effects and applications of arthropod steroid hormones (ecdysteroids) in mammals. J Endocrinol. 2006;191(1):1–8.
- Báthori M, Tóth N, Hunyadi A, Márki A, Zádor E. Phytoecdysteroids and anabolic-androgenic steroids: structure and effects on humans. Curr Med Chem. 2008;15(1):75–91.
- Ambrosio G, Wirth D, Joseph JF, et al. How reliable is dietary supplement labelling? Experiences from the analysis of ecdysterone supplements. J Pharm Biomed Anal. 2020;177:112877.
