Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Head-to-head comparison of Enclomiphene and Endoxifen — mechanism, side effects, legal status, and pricing.
Enclomiphene is the trans-stereoisomer of clomiphene citrate, a non-steroidal selective estrogen receptor modulator (SERM) that stimulates endogenous testosterone production. It is not a peptide, but is widely tracked in the peptide and TRT community as an off-label, compounded alternative to testosterone replacement therapy for men who wish to preserve fertility. Clomiphene itself is a ~60:40 mixture of enclomiphene (trans, estrogen-antagonist) and zuclomiphene (cis, weak long-acting estrogen-agonist); isolating the trans-isomer is intended to deliver the HPG-axis effect without the zuclomiphene-driven side effects.
Endoxifen is a non-steroidal triphenylethylene selective estrogen receptor modulator (SERM) and the active secondary metabolite of tamoxifen. It is not FDA-approved and remains investigational, studied in multiple Phase 1 and Phase 2 human trials for endocrine-refractory ER-positive breast cancer, desmoid tumors, and other hormone-receptor-positive solid tumors. Endoxifen is sold by research-chemical suppliers labeled for laboratory use only, not for human consumption.
Enclomiphene
Endoxifen
Category
Legal Status
Mechanism
Half-life
Side Effects
COA-verified vendors · trust score ≥70 required · single-vial price — bulk/bundle deals may be lower
Enclomiphene
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Check Enclomiphene prices →Endoxifen
COA corpus from Disclosed Labs — independently tested batches only.
Enclomiphene
3
COAs
99.6%
Avg purity
1
Labs
Endoxifen
2
COAs
99.5%
Avg purity
2
Labs
Wiehle et al. (BJU Int 2013, PMID 23875626) established pharmacokinetics and demonstrated testosterone restoration to the normal range in men with secondary hypogonadism. Kaminetsky et al. (J Sex Med 2013, PMID 23530575) showed enclomiphene raised testosterone and sperm counts while testosterone gel suppressed gonadotropins and spermatogenesis. Phase 3 trials ZA-304 and ZA-305 (Kim et al., BJU Int 2016, PMID 26496621) confirmed efficacy in overweight/obese hypogonadal men with superior preservation of LH, FSH, and sperm counts versus AndroGel 1.62%. Despite these positive data, the FDA issued Complete Response Letters to Repros Therapeutics in 2014 and 2016; Androxal was never approved and Repros subsequently wound down. As of April 2026 no FDA-approved enclomiphene exists. It is dispensed off-label via 503A compounding pharmacies for secondary hypogonadism and post-TRT/HPTA restart.
Key references
No FDA approval or approval in any jurisdiction; endoxifen is investigational only. Human trials: Goetz et al. 2017 Phase 1 in endocrine-refractory metastatic ER-positive breast cancer (20–160 mg/day oral, no maximum tolerated dose, 3 partial responses, clinical benefit rate 26.3%); Takebe et al. 2021 Phase 1 in gynecologic, desmoid, and hormone-receptor-positive solid tumors (20–360 mg/day, no MTD, partial responses in desmoid tumors); Alliance A011203 randomized Phase 2 found Z-endoxifen not superior to tamoxifen overall but showed PFS benefit in CDK4/6-inhibitor-naive patients (HR 0.42). Preclinical: in ovariectomized mice, oral Z-endoxifen increased cancellous and cortical bone mass; in rats, reduced bone turnover and protected against bone loss; in MCF7 xenografts, showed superior antitumor activity versus tamoxifen, letrozole, and exemestane.
Enclomiphene and Endoxifen are both in the Hormone category and may have overlapping mechanisms. Researchers should review both profiles carefully, understand the mechanisms of action, and monitor the relevant biomarkers when combining compounds in the same class. As always, consult a licensed healthcare provider before making any decisions about combining research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
Contraindications
Lab Testing
Key references
Disclosed Labs