Enclomiphene

Overview

Enclomiphene is the trans-stereoisomer of clomiphene citrate, a non-steroidal selective estrogen receptor modulator (SERM). It is not a peptide, but is widely tracked alongside peptides in the men's-health research community as a compounded, fertility-sparing alternative to testosterone replacement. Clomiphene is a mixture of enclomiphene (the estrogen-antagonist trans-isomer) and zuclomiphene (a weak long-acting estrogen-agonist cis-isomer); isolating enclomiphene aims to deliver the HPG-axis effect without the zuclomiphene-driven drawbacks. No FDA-approved enclomiphene product exists as of 2026.

Mechanism of Action

Enclomiphene blocks estrogen receptors at the hypothalamus, disinhibiting GnRH pulse generation. The resulting rise in LH and FSH stimulates testicular Leydig-cell testosterone production and Sertoli-cell spermatogenesis. Because it lacks the estrogenic zuclomiphene component and is not exogenous testosterone, it raises endogenous testosterone without suppressing gonadotropins or intratesticular testosterone.

Research Summary

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.

Prescribers who offer Enclomiphene

22 prescribers in our directory work with Enclomiphene, each confirmed from their own website. Peptides like Enclomiphene require a prescription from a licensed provider — telehealth options are available.

Reported Side Effects

• Headache
• Nausea
• Hot flashes
• Mood changes
• Visual disturbances — blurred vision, light sensitivity, scintillations (SERM class effect; discontinue if they occur)
• Thromboembolism (rare SERM class effect)

Biomarkers researchers track for Enclomiphene

These biomarkers appear in the research literature as measures of response and safety for this compound.

Related Peptides

Compare Enclomiphene with Others

Research References

• Wiehle RD, et al. Enclomiphene citrate stimulates testosterone production while preventing oligospermia. Fertil Steril. 2014;102(3):720-727.
• Kaminetsky J, et al. Oral enclomiphene citrate raises testosterone and preserves sperm counts in obese hypogonadal men. J Sex Med. 2013;10(6):1628-1635.
• Repros Therapeutics. Androxal (enclomiphene) Phase 3 trials ZA-304 and ZA-305; FDA Complete Response Letters, 2014 and 2016.

Frequently asked questions

Has Enclomiphene been independently lab-tested?

Disclosed Labs has collected 3 Certificates of Analysis (COA) for Enclomiphene from 1 independent testing lab. 1 vendor has submitted material for testing. Products average 99.6% tested purity across the corpus. Full testing data is available at https://www.disclosedlabs.com/peptides/enclomiphene/testing.

What is the average purity of Enclomiphene on the market?

Based on 3 COAs analyzed by Disclosed Labs, Enclomiphene products average 99.6% (±0.1%) tested purity. Individual vendor results vary; see per-vendor COA data at https://www.disclosedlabs.com/peptides/enclomiphene/coas.

Which prescribers offer Enclomiphene with a prescription?

22 prescribers in the Disclosed Labs directory work with Enclomiphene, each confirmed from their own website, with telehealth options available. Enclomiphene requires a prescription from a licensed provider. Browse them at https://www.disclosedlabs.com/prescribers?peptide=Enclomiphene.

How does Enclomiphene work?

Enclomiphene blocks estrogen receptors at the hypothalamus, disinhibiting GnRH pulse generation. The resulting rise in LH and FSH stimulates testicular Leydig-cell testosterone production and Sertoli-cell spermatogenesis. Because it lacks the estrogenic zuclomiphene component and is not exogenous testosterone, it raises endogenous testosterone without suppressing gonadotropins or intratesticular testosterone.

What does the research say about Enclomiphene?

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.