Clomiphene (Clomid) is a fertility drug developed for women. It triggers ovulation with a 5-day course once per cycle, and it works well for that. It is a mix of two molecules: about 62% enclomiphene and 38% zuclomiphene (FDA prescribing information).
Enclomiphene is the half that is useful for men. It blocks estrogen receptors in the brain, so the pituitary releases more LH and FSH and your testes make more of your own testosterone. Zuclomiphene is the problem half for men. It acts like a weak estrogen, works against the effect you want, and clears very slowly: detectable levels last more than a month, while enclomiphene is gone in about 10 hours. On a 5-day course that does not matter. A man with low testosterone takes the drug every day for months, so zuclomiphene builds up. The side effects men report on long-term Clomid, mood swings, hot flashes, breast tenderness, and visual disturbances, are thought to come from that estrogen-like build-up. Clomid is a poor fit for daily, long-term use in men.
Enclomiphene was isolated from that mix and developed as a standalone drug specifically for men with secondary hypogonadism. In trials it raised testosterone into the normal range while keeping sperm counts normal (Wiehle et al., Fertility and Sterility, 2014; Kaminetsky et al., BJU International, 2016), and a 2025 meta-analysis of 10 randomized trials found SERM therapy raised total testosterone by 274 ng/dL over placebo while preserving sperm production (Hohl et al., Archives of Endocrinology and Metabolism, 2025).
Enclomiphene is available only from compounding pharmacies, so no insurance covers it and most primary care doctors never prescribe it. Veedma prescribes it as the first-line testosterone treatment, works with compounding pharmacies that make it, and monitors every man on it with follow-up labs after the first month and every 6 months.