Ecdysterone (20-Hydroxyecdysone) — Safety, Research, Risks & Legal Status

Not medical advice. Ecdysterone (20-Hydroxyecdysone) is discussed here for informational and harm-reduction purposes only. We do not endorse use, and any dosing context is informational, not a protocol.

Also known as	20E; 20-Hydroxyecdysone; beta-ecdysone; ecdysterone (supplement trade name)
Category	Supplement
Natural source	Found in spinach, quinoa, amaranth; classified as a phytoecdysteroid
Receptor target	Primarily estrogen receptor beta (ERbeta); MAS1 receptor agonism also proposed; androgen receptor binding not demonstrated
WADA status (2025)	Prohibited - classified S1.2 Other Anabolic Agents, banned in and out of competition
Largest human RCT	46 young men, 10 weeks, 175-350 mg/day; approximately 2 kg lean mass gain vs. placebo (Isenmann et al., 2019)
Oral bioavailability	Restricted; peak serum levels at 3-8.5 hours, half-life approximately 3 hours
Preclinical safety signal	Kidney enlargement and early chronic kidney injury in long-term mouse studies; not yet observed in short human trials
US legal status	Legal in the United States as a dietary supplement; not FDA-approved as a drug and not a controlled substance. No FDA restrictions on sale or marketing as of 2025. WADA 2025 Prohibited List classifies ecdysterone as a prohibited anabolic agent (S1.2, "other anabolic agents"), banned in and out of competition for athletes subject to anti-doping rules. Not prohibited for general non-athlete consumers under US law.

What is Ecdysterone (20-Hydroxyecdysone)?

Ecdysterone (20-hydroxyecdysone, 20E) is a naturally occurring ecdysteroid - a steroid hormone analog found in insects and in certain plants including spinach, quinoa, and amaranth. It is structurally related to insect molting hormones but is not a conventional anabolic-androgenic steroid (AAS) and does not bind the androgen receptor. It is commercially available as a dietary supplement and has attracted research interest as a potential non-androgenic ergogenic and anabolic agent.

How it works

The precise mammalian mechanism remains partially unresolved. Evidence points to selective activation of estrogen receptor beta (ERbeta), hypothesized to mediate muscle hypertrophy without androgenic effects. Additional proposed mechanisms include MAS1 receptor agonism (the protective arm of the renin-angiotensin system), upregulation of glycolytic and one-carbon metabolism enzymes, and elevation of cytoplasmic calcium with sustained Akt activation leading to increased protein synthesis - approximately 20% elevation observed in human and mouse myotube studies. Whether the primary effector is ERbeta, a novel membrane-bound GPCR, or a combination remains an open question in the literature.

Background & history

Ecdysterone is a natural phytochemical with a long ethnobotanical history in plants used as food (spinach, amaranth, quinoa). Soviet-era sports science in the 1980s-1990s investigated ecdysteroids as non-androgenic performance aids. Academic interest was revived in the 2010s through WADA-funded anti-doping research at German and Italian laboratories, which produced the most cited modern RCT (Isenmann et al., 2019). WADA added ecdysterone to its Monitoring List in 2024 and elevated it to the Prohibited List (S1.2) in 2025, reflecting growing concern about ergogenic use in competitive sport. No pharmaceutical company has advanced it through formal drug development, and it remains entirely in the supplement and academic research space.

What the research says

Human evidence is modest and conflicting. The most cited study is a 10-week RCT in 46 young men (Isenmann et al., 2019, WADA-supported) showing significantly greater lean mass gains (approximately 2.0 kg) and one-repetition bench press improvement with 175-350 mg/day versus placebo. A Phase 2b-type study in elderly individuals with sarcopenia reported improved walking speed and lower-limb function at 175-350 mg twice daily over 6-9 months. A study in 78 highly trained athletes reported approximately 6-7% lean mass increase and roughly 10% fat reduction with protein co-supplementation. However, at least one RCT in resistance-trained men found no statistically significant difference versus placebo, meaning the literature is not uniformly positive. Preclinical data in C2C12 murine and human primary myotubes show 15-20% elevated protein synthesis. Long-term human data are absent; the longest human trials are approximately 10-12 weeks. Preclinical (mouse) studies have identified potential kidney enlargement and early chronic kidney injury signals with long-term exposure. Overall, human evidence is preliminary and limited; larger, longer, and more rigorous trials are needed.

Reported effects

Modest lean muscle mass gain in short-term RCTs (approximately 2 kg over 10 weeks in one trial versus placebo)
Improvement in resistance-exercise performance metrics (bench press 1RM in one RCT)
Potential improvement in walking speed and lower-limb function in elderly (one sarcopenia study)
Increased protein synthesis in human and murine myotube models (preclinical, approximately 15-20% elevation)
No androgenic side effects observed in short-term human trials (no libido, mood, or hormonal disruption reported)
At least one RCT in trained athletes found no significant ergogenic effect versus placebo - efficacy is not uniformly established
Evidence for fat reduction when co-administered with protein supplementation (one study, 78 athletes)

Dosing & administration (informational)

Human research trials have generally used 175-350 mg per day (some protocols twice daily) for 6-12 weeks, sometimes in combination with protein supplementation. These are the ranges reported in published literature and are provided for informational reference only. Oral bioavailability is restricted; peak serum levels occur 3-8.5 hours post-dose with an approximately 3-hour half-life. No dosing protocol should be derived from this entry. Consult a licensed clinician before using any supplement.

This is general research/context information, not medical advice or a recommended protocol.

Safety & side effects

Short-term human trials (up to 12 weeks) show a favorable safety profile with no clinically significant liver or kidney biomarker elevation
Most common adverse event: mild, transient gastrointestinal distress (nausea, upset stomach), dose-dependent
Appetite changes and mild sleep alterations reported in some participants but not considered severe
Acute rodent LD50 exceeds 9,000 mg/kg, indicating a wide safety margin at doses used in human studies
Preclinical concern: chronic mouse studies identified kidney enlargement and early chronic kidney injury signals; long-term human kidney safety is unknown
Long-term human safety data are entirely absent; no trial has exceeded approximately 12 weeks
Contraindicated or use with caution in pregnancy, breastfeeding, hormone-sensitive conditions (ERbeta activity is a theoretical concern), and with ACE inhibitors or ARBs (MAS1 agonism)

Drug & supplement interactions

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Who should avoid it

Pregnancy and breastfeeding (no safety data; theoretical estrogenic receptor activity)
Hormone-sensitive conditions (estrogen receptor-positive cancers, endometriosis, uterine fibroids) until data exist
Concurrent use of ACE inhibitors or ARBs without clinician oversight (MAS1 agonism)
Competitive athletes subject to anti-doping rules (WADA 2025 Prohibited List, S1.2, in and out of competition)
Individuals with pre-existing kidney disease given preclinical kidney signals in long-term animal models
Any use where long-term safety is a primary concern given the complete absence of long-term human data

How it is commonly combined

No evidence-based stacking protocols exist. Research trials have occasionally co-administered ecdysterone with protein supplementation (whey), and one study in 78 trained athletes reported enhanced lean mass and fat loss in that context. No pharmacokinetic or pharmacodynamic data support specific stacking combinations, and no safety data exist for multi-agent protocols. Given WADA prohibited status, any stacking consideration for competitive athletes is precluded by the ban.

Legal & regulatory. Legal in the United States as a dietary supplement; not FDA-approved as a drug and not a controlled substance. No FDA restrictions on sale or marketing as of 2025. WADA 2025 Prohibited List classifies ecdysterone as a prohibited anabolic agent (S1.2, "other anabolic agents"), banned in and out of competition for athletes subject to anti-doping rules. Not prohibited for general non-athlete consumers under US law.

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Frequently asked questions

Is ecdysterone legal to buy in the United States?

Yes. Ecdysterone is not a controlled substance and is legally sold as a dietary supplement in the US with no FDA restrictions as of 2025. However, it is prohibited by WADA for competitive athletes as of the 2025 Prohibited List (S1.2 Other Anabolic Agents), so athletes subject to anti-doping rules must not use it regardless of its civilian legal status.

Does ecdysterone work like a steroid?

It is not a conventional anabolic-androgenic steroid and does not bind the androgen receptor. Evidence points to estrogen receptor beta activation and other non-androgenic pathways as the primary mechanism. This means it does not produce typical AAS-associated effects such as testosterone suppression, virilization, or hormonal disruption - at least not in available short-term human trials. Whether the anabolic effect is meaningfully comparable to AAS in magnitude is not established.

What does the human research actually show?

The evidence is modest and mixed. The most cited RCT (Isenmann et al., 2019, n=46, 10 weeks) showed significantly greater lean mass gains and bench press improvement versus placebo. A study in elderly individuals with sarcopenia suggested functional improvements. At least one study in resistance-trained men found no statistically significant benefit. The literature is too limited and inconsistent to draw firm efficacy conclusions, and no trials have exceeded approximately 12 weeks.

What is the recommended dose?

This reference does not provide dosing recommendations. Published research trials have used 175-350 mg per day, sometimes twice daily, but these are experimental parameters reported in the literature, not clinical guidance. Consult a licensed clinician before using ecdysterone or any supplement.

Are there known safety concerns?

Short-term trials up to 12 weeks have not identified significant liver or kidney toxicity in humans. The most common side effect is mild gastrointestinal discomfort. The meaningful concern is the absence of long-term human safety data combined with preclinical mouse studies showing kidney enlargement and early chronic kidney injury signals with chronic exposure. Anyone with kidney disease, hormone-sensitive conditions, or who is pregnant or breastfeeding should avoid use until more data exist.

Why did WADA ban it in 2025?

WADA placed ecdysterone on its Monitoring List in 2024 following commissioned research, including the Isenmann 2019 RCT, suggesting meaningful ergogenic potential. In 2025, WADA elevated it to the Prohibited List under S1.2 Other Anabolic Agents, citing evidence of anabolic activity via non-androgenic pathways. This ban applies in and out of competition for athletes in sports governed by WADA-compliant anti-doping programs.

References & further reading

PubMed: ecdysteroids anabolic muscle Isenmann 2019 (PMID 31123801 - seminal 10-week RCT)
PubMed: 20-hydroxyecdysone MAS1 receptor renin-angiotensin (PMID 34825653)
PubMed: ecdysterone urinary elimination pharmacokinetics (PMC8227119)
PubMed: 20-hydroxyecdysone muscle protein synthesis estrogen receptor beta
ClinicalTrials.gov: search term 'ecdysterone' (limited active registrations as of 2025)