Clomifene

Hormonal / PCT

Also known as: Clomid, Clomiphene, Clomiphene Citrate, CC

Selective Estrogen Receptor ModulatorsResearch phase: FDA-approvedRegulatory: FDA-approved for ovulatory dysfunction in women (1967). Used off-label for male hypogonadism and PCT. Available by prescription as Clomid and generics.

Mechanism

Clomifene (Clomid) is an FDA-approved SERM primarily used to induce ovulation in women with fertility issues. In the male health and performance community, it is widely used off-label to raise testosterone by blocking estrogen feedback at the pituitary, stimulating LH and FSH release. It is a racemic mixture of two isomers — enclomifene (anti-estrogenic) and zuclomifene (weakly estrogenic).

Technical detail

Clomifene citrate is a racemic mixture of enclomifene (~62%) and zuclomifene (~38%) isomers. Enclomifene is the pharmacologically active anti-estrogenic isomer responsible for hypothalamic-pituitary ER antagonism, blocking estrogen negative feedback and increasing GnRH pulsatility, resulting in elevated LH, FSH, and consequent testosterone production. Zuclomifene has longer half-life and weak estrogenic activity that may partially counteract the anti-estrogenic effects. Off-label use in male hypogonadism typically produces testosterone increases of 200-400 ng/dL with concurrent improvements in spermatogenesis.

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