Enclomiphene
A medication that boosts natural testosterone production by blocking estrogen's feedback signal in the brain. Used in men's health clinics as an alternative to testosterone shots that preserves fertility and testicular function. Unlike mixed clomiphene (Clomid), enclomiphene lacks the estrogen-like component (zuclomiphene) that causes many of clomiphene's side effects.
Dosage
12.5-25 mg oral once daily
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Administration
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Effects
Testosterone Elevation
Blocks estrogen feedback to increase endogenous testosterone production.
Fertility Preservation
Preserves spermatogenesis unlike exogenous testosterone replacement.
Hormone Balance
Restores natural hormone feedback by selectively blocking estrogen at the pituitary.
Mechanism of Action
Enclomiphene is the trans-stereoisomer of clomiphene citrate, a selective estrogen receptor modulator (SERM). Clomiphene (Clomid) contains a roughly equal mixture of two geometric isomers: enclomiphene (trans) and zuclomiphene (cis). Enclomiphene is the pharmacologically desired isomer for testosterone elevation because it acts as a pure estrogen receptor antagonist in the hypothalamus and pituitary, while zuclomiphene has mixed agonist/antagonist activity that can cause unwanted estrogenic effects and has a much longer half-life (weeks), accumulating with chronic dosing.
Enclomiphene competitively binds to estrogen receptors (ERα) in the hypothalamus and anterior pituitary gland, blocking the binding of circulating estradiol. Normally, estradiol exerts negative feedback on the hypothalamic-pituitary axis: estradiol binding to ERα in the hypothalamus reduces GnRH pulse frequency and amplitude, while estradiol binding in the pituitary reduces gonadotroph sensitivity to GnRH. By blocking these receptors, enclomiphene removes the negative feedback signal — the hypothalamus 'perceives' low estrogen levels regardless of actual estradiol concentrations and responds by increasing GnRH pulse frequency. The pituitary, also freed from estrogen-mediated suppression, responds more robustly to each GnRH pulse, producing increased LH and FSH secretion.
Elevated LH stimulates Leydig cells in the testes to produce more testosterone (via the LHCGR/cAMP/StAR steroidogenic pathway), while elevated FSH stimulates Sertoli cells to support spermatogenesis. This is the critical advantage of enclomiphene over exogenous testosterone replacement: it raises endogenous testosterone production through the natural HPG axis while preserving (and potentially enhancing) fertility. Exogenous testosterone, by contrast, suppresses LH/FSH through negative feedback, causing testicular atrophy and often azoospermia. The 10-hour half-life of enclomiphene allows once-daily dosing, and its pure antagonist profile at ERα avoids the estrogenic side effects (hot flashes, visual disturbances, mood changes) that zuclomiphene contributes in mixed clomiphene formulations.
Regulatory Status
Not FDA approved as a standalone drug (Androxal failed to gain approval). Available through compounding pharmacies. Clomiphene citrate (which contains both isomers) is FDA approved for female ovulatory dysfunction.
Risks & Safety
Common
headache, nausea, hot flashes, mild mood changes.
Serious
visual disturbances (blurred vision, seeing flashes of light — less common than with mixed clomiphene), potential overstimulation of testosterone production.
Rare
blood clots (SERM class effect), significant mood changes, visual blind spots. Significantly fewer estrogenic side effects than clomiphene (Clomid) due to absence of zuclomiphene.
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Research Papers
1Published: October 8, 2025
AI Summary
A meta-analysis of randomized trials evaluated the efficacy and safety of clomiphene and enclomiphene for treating men with functional hypogonadism. The review synthesized evidence on how these SERMs perform compared to other approaches.
Frequently Asked Questions
What is Enclomiphene?
A medication that boosts natural testosterone production by blocking estrogen's feedback signal in the brain. Used in men's health clinics as an alternative to testosterone shots that preserves fertility and testicular function. Unlike mixed clomiphene (Clomid), enclomiphene lacks the estrogen-like component (zuclomiphene) that causes many of clomiphene's side effects.
What is Enclomiphene used for?
A medication that boosts natural testosterone production by blocking estrogen's feedback signal in the brain. Used in men's health clinics as an alternative to testosterone shots that preserves fertility and testicular function. Unlike mixed clomiphene (Clomid), enclomiphene lacks the estrogen-like component (zuclomiphene) that causes many of clomiphene's side effects.
What is the dosage for Enclomiphene?
Standard: 12.5-25 mg oral once daily. Some protocols use up to 50 mg. Often used as monotherapy for secondary hypogonadism or alongside GH peptides. Continuous use or cycled depending on protocol and lab monitoring.
What are the side effects of Enclomiphene?
Common: headache, nausea, hot flashes, mild mood changes. Serious: visual disturbances (blurred vision, seeing flashes of light — less common than with mixed clomiphene), potential overstimulation of testosterone production. Rare: blood clots (SERM class effect), significant mood changes, visual blind spots. Significantly fewer estrogenic side effects than clomiphene (Clomid) due to absence of zuclomiphene.
How does Enclomiphene work?
Enclomiphene is the trans-stereoisomer of clomiphene citrate, a selective estrogen receptor modulator (SERM). Clomiphene (Clomid) contains a roughly equal mixture of two geometric isomers: enclomiphene (trans) and zuclomiphene (cis). Enclomiphene is the pharmacologically desired isomer for testosterone elevation because it acts as a pure estrogen receptor antagonist in the hypothalamus and pituitary, while zuclomiphene has mixed agonist/antagonist activity that can cause unwanted estrogenic effects and has a much longer half-life (weeks), accumulating with chronic dosing. Enclomiphene competitively binds to estrogen receptors (ERα) in the hypothalamus and anterior pituitary gland, blocking the binding of circulating estradiol. Normally, estradiol exerts negative feedback on the hypothalamic-pituitary axis: estradiol binding to ERα in the hypothalamus reduces GnRH pulse frequency and amplitude, while estradiol binding in the pituitary reduces gonadotroph sensitivity to GnRH. By blocking these receptors, enclomiphene removes the negative feedback signal — the hypothalamus 'perceives' low estrogen levels regardless of actual estradiol concentrations and responds by increasing GnRH pulse frequency. The pituitary, also freed from estrogen-mediated suppression, responds more robustly to each GnRH pulse, producing increased LH and FSH secretion. Elevated LH stimulates Leydig cells in the testes to produce more testosterone (via the LHCGR/cAMP/StAR steroidogenic pathway), while elevated FSH stimulates Sertoli cells to support spermatogenesis. This is the critical advantage of enclomiphene over exogenous testosterone replacement: it raises endogenous testosterone production through the natural HPG axis while preserving (and potentially enhancing) fertility. Exogenous testosterone, by contrast, suppresses LH/FSH through negative feedback, causing testicular atrophy and often azoospermia. The 10-hour half-life of enclomiphene allows once-daily dosing, and its pure antagonist profile at ERα avoids the estrogenic side effects (hot flashes, visual disturbances, mood changes) that zuclomiphene contributes in mixed clomiphene formulations.
How is Enclomiphene administered?
Enclomiphene is administered via oral.
What is the half-life of Enclomiphene?
The half-life of Enclomiphene is 10 hours.
Is Enclomiphene legal?
Not FDA approved as a standalone drug (Androxal failed to gain approval). Available through compounding pharmacies. Clomiphene citrate (which contains both isomers) is FDA approved for female ovulatory dysfunction.
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