Clomiphene Citrate (Clomid, Serophene)

Clomiphene citrate occupies an unusual place in men's health. It's FDA approved only for female ovulation induction, but it's one of the most widely prescribed off-label treatments for male hypogonadism, particularly in younger men who want to raise testosterone without sacrificing fertility. The drug is actually a mixture of two stereoisomers: enclomiphene (trans-isomer) and zuclomiphene (cis-isomer), present in roughly a 62:38 ratio in the commercial product. This matters clinically because the two isomers have different pharmacological profiles. Enclomiphene is the active anti-estrogen that blocks hypothalamic estrogen receptors and drives the LH/FSH increase. Zuclomiphene has a much longer half-life (over 30 days vs. 10 hours for enclomiphene) and actually has weak estrogenic activity. Over months of use, zuclomiphene accumulates, which may explain why some men on clomiphene get good lab numbers but still don't feel great. This isomer problem is exactly why enclomiphene (the isolated trans-isomer, discussed in a separate entry) was developed as a standalone compound. Repros Therapeutics ran Phase 3 trials for enclomiphene (Androxal) seeking specific approval for male secondary hypogonadism, but the FDA sent a Complete Response Letter and the program stalled. The clinical data for clomiphene in men is solid for lab endpoints. Katz et al. (PMID: 21592302) followed 86 men on clomiphene 25-50 mg every other day for a mean of 19 months. Average testosterone rose from 228 to 612 ng/dL, and semen parameters were maintained. Guay et al. (PMID: 12843171) showed similar testosterone increases with improvements in sexual function scores. The practical limitation is that clomiphene raises both testosterone and estradiol. Some men develop symptoms of high estradiol (water retention, nipple sensitivity, mood changes) even though their testosterone levels look good. This is why some clinicians combine clomiphene with a low-dose aromatase inhibitor, though this combination requires careful monitoring to avoid crashing estradiol too low. Dosing in men is much lower than in female fertility protocols. Most male protocols start at 25 mg every other day or 25 mg daily, adjusting based on lab response. Some clinicians use as little as 12.5 mg daily. Higher doses don't necessarily produce better results and increase the risk of visual side effects and estradiol elevation. Visual disturbances are the most concerning side effect, occurring in roughly 1-2% of users. These include blurred vision, light trails, and floaters. They're typically reversible after discontinuation, but any visual changes should prompt immediate cessation. Clomiphene is best suited for men with secondary hypogonadism, meaning the problem is at the hypothalamic-pituitary level rather than the testes themselves. In primary hypogonadism (testicular failure), the testes can't respond to increased LH stimulation, making clomiphene ineffective. An easy diagnostic clue: if LH is already elevated (above 9-10 mIU/mL), clomiphene probably won't work because the issue is downstream. Cost is one of clomiphene's biggest advantages. Generic clomiphene citrate runs $15-40/month, making it far cheaper than injectable testosterone, testosterone gels, or newer alternatives. For younger men exploring options before committing to lifelong TRT, clomiphene offers a reversible trial that preserves the HPG axis.