Clomid for men, and the paragraph on the label that is about you

What is clomiphene?

Clomiphene citrate is a selective estrogen receptor modulator, an oral tablet that the label says may compete with estrogen for receptor binding sites in tissues including the hypothalamus and pituitary. Its first endocrine effect, in the label's words, is an increase in the release of pituitary gonadotropins, which is luteinizing hormone and follicle stimulating hormone, and those two signals tell the testes to make more of their own testosterone and to keep producing sperm. Clomiphene is a mixture of two isomers, zuclomiphene and enclomiphene, which is why clomiphene and enclomiphene name the same chemistry at two different degrees of purification.

Clomiphene citrate is FDA-approved, and approved only for ovulatory dysfunction in women. Enclomiphene has no FDA-approved product and is dispensed as a compounded preparation, so it is not reviewed by the FDA for potency, quality or this use. Our full enclomiphene explainer.

Is Clomid FDA-approved for men?

No, and the record is short enough to check in two clicks. Clomid was approved on February 1, 1967 under NDA 016131, held then by Sanofi Aventis US. That record now shows the product as Discontinued, with the note that this was a Federal Register determination that product was not discontinued or withdrawn for safety or effectiveness reasons. The Clomid on pharmacy shelves today is ANDA 075528, Cosette Pharmaceuticals, first approved August 30, 1999. Neither application carries a male indication.

The approved indication reads in full: “Clomiphene citrate is indicated for the treatment of ovulatory dysfunction in women desiring pregnancy.” Prescribing an approved drug outside its approved indication is legal, ordinary medicine, and it happens across every specialty. The reason it matters here is what the same section goes on to say.

Read that paragraph the way the label wrote it, which is carefully. The tumour sentence is a report of an association with the causal question left open, and the label says so in its own next sentence. The effectiveness sentence is about male infertility rather than about testosterone. Read together, they are the manufacturer, under FDA review, declining to claim the thing the clinics are selling. Take it as information and ask the prescriber to respond to it.

Clomid against enclomiphene: the same drug, minus one isomer

The composition is on the label: “Clomiphene citrate is a mixture of two geometric isomers [cis (zuclomiphene) and trans (enclomiphene)] containing between 30% and 50% of the cis-isomer.” Read the range the other way and enclomiphene, the trans isomer, is 50 to 70 percent of what is in a Clomid tablet, calculated from the label figure. Enclomiphene is that fraction, sold on its own.

The case for separating them is also on the label, in two sentences that the marketing pages paraphrase and rarely quote: “Some data suggest that zuclomiphene has greater estrogenic activity than enclomiphene.” and “Subsequent single-dose studies in normal volunteers showed that zuclomiphene (cis) has a longer half-life than enclomiphene (trans). Detectable levels of zuclomiphene persisted for longer than a month in these subjects.” Note that the label hedges the first claim and puts no number on the half-life. An isomer some data suggest is more estrogenic, and whose levels stayed detectable for longer than a month in those studies, is a plausible source of the mood and breast-tissue complaints men report on clomiphene, and that is the argument for taking the other one alone. The label supports the pharmacology. It does not test the clinical claim.

The head-to-head evidence in men is retrospective rather than randomized. Retrospective comparison of clomiphene citrate against enclomiphene citrate in men aged 18 and over with primary infertility, abnormal semen parameters or hypogonadism, treated with one or the other as monotherapy for at least three months between January 2021 and December 2022: 46 men on enclomiphene and 32 on clomiphene. Total testosterone rose significantly in both groups. Only the enclomiphene group showed a statistically significant rise in FSH and LH, and only that group showed a significant rise in total motile sperm count. Semen volume and concentration did not change significantly on either drug. The limit: Retrospective, 78 men in total, not randomized, and the authors declare financial relationships. Thomas J et al., Cureus, 2023.

The paperwork runs backwards, and here is where to check it

Enclomiphene had its shot at approval and the record is public. A Federal Register notice published August 20, 2015 called the Bone, Reproductive, and Urologic Drugs Advisory Committee to discuss “new drug application (NDA) 207959, enclomiphene citrate 12.5 milligram (mg) and 25 mg capsules, submitted by Repros Therapeutics, Inc., for the proposed treatment of secondary hypogonadism in fertile men (men with more than 15 million sperm/milliliter (ml)), younger than 60 years of age with a Body Mass Index (BMI) over 25 kilograms (kg)/meters squared (m2)” Searched on August 16, 2026, NDA 207959 returns no record in Drugs@FDA. There is no approved enclomiphene product to point at, which is what our enclomiphene explainer says too.

The compounding record is the part almost nobody has read. Enclomiphene citrate was nominated for the 503A Bulks List, the list of bulk substances a pharmacy may compound from when no US Pharmacopeia monograph exists and the substance is not a component of an approved drug. The meeting notice states the single use FDA evaluated it for: “To increase serum testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) to normal levels in the treatment of secondary hypogonadism.” The Pharmacy Compounding Advisory Committee took it up on June 8, 2022 under docket FDA-2021-N-0357, alongside ammonium tetrathiomolybdate, ferric subsulfate and glutathione.

hCG for men, and what it does differently

hCG is the odd one out in this category, because it is the only one of the three routes with an FDA-approved male indication. The chorionic gonadotropin label lists three indications and the second is “Selected cases of hypogonadotropic hypogonadism (hypogonadism secondary to a pituitary deficiency) in males.” The application is BLA 017067, held by Fresenius Kabi USA, and the strength still marketed on that record is the 10,000 units per vial. The other two cover prepubertal cryptorchidism not due to anatomical obstruction, and induction of ovulation and pregnancy in the anovulatory, infertile woman in whom the cause of anovulation is secondary and not due to primary ovarian failure, and who has been appropriately pretreated with human menotropins. Read the male one closely, because a TRT clinic is generally using hCG for something narrower than what it says: keeping the testes working in a man whose own signal is suppressed by the testosterone he is already taking is a different situation from the pituitary deficiency the label names.

The mechanical difference is the reason a clinic reaches for it. Clomiphene works upstream, on the brain, so it needs a pituitary that can still respond to being unblocked. hCG skips that step. The label puts it plainly: “The action of HCG is virtually identical to that of pituitary LH, although HCG appears to have a small degree of FSH activity as well. It stimulates production of gonadal steroid hormones by stimulating the interstitial cells (Leydig cells) of the testis to produce androgens and the corpus luteum of the ovary to produce progesterone.” An LH analog acting directly on Leydig cells will work in a man whose own LH is flat, including a man whose LH is flat because he is already on testosterone.

Head to head with clomiphene, the one randomized comparison found no winner on testosterone. 282 men with hypogonadism who wanted to preserve fertility, randomized to clomiphene citrate 50 mg (n=95), hCG 5,000 IU twice weekly (n=94), or both (n=94), measured at baseline, one month and three months. Testosterone rose in all three arms to a final mean of 5.17 nmol/L, a 223 percent increase from a baseline mean of 2.31 nmol/L, with no statistically significant difference between the arms. Symptom scores improved most in the combination arm (P less than 0.01). The authors concluded all three treatments were equally effective at restoring testosterone and that single-agent clomiphene is simple and cheap. Three months is a short course, and the trial reports no sperm outcome, so it settles the testosterone question and not the fertility one. Habous M et al., BJU International, 2018.

One regulatory wrinkle worth knowing before you shop. On March 23, 2020, under section 7002(e) of the BPCI Act, approved applications for a set of protein products were deemed to be biologics license applications, and the Federal Register document explaining the change names chorionic gonadotropin among them. That is why the application number above starts with BLA rather than NDA. Separately, 21 CFR 216.24 bars compounding of “Gonadotropin, chorionic: All drug products containing chorionic gonadotropins of animal origin.”

Why this category exists at all: fertility

Strip away the marketing and there is one reason a man ends up researching clomiphene instead of testosterone. Testosterone taken from outside shuts down the signals that keep sperm production running, and the testosterone cypionate label states the mechanism itself: “During exogenous administration of androgens, endogenous testosterone release is inhibited through feedback inhibition of pituitary luteinizing hormone (LH). At large doses of exogenous androgens, spermatogenesis may also be suppressed through feedback inhibition of pituitary follicle stimulating hormone (FSH).”Note the hedge the label uses, “may also be suppressed”, and note that it attaches the effect to large doses. In its precautions the same label adds “Oligospermia may occur after prolonged administration or excessive dosage.” and its adverse-reaction list for men includes testicular atrophy, subfertility, and infertility.

Clomiphene raises those same signals rather than replacing the hormone downstream of them, which is the whole trade. What the evidence actually supports, and its limits:

• Systematic review and meta-analysis of clomiphene citrate in infertile men: 18 studies in the qualitative analysis (n=731), 15 pooled (n=566). Sperm concentration was higher during treatment by a mean difference of 8.38 million per mL (95% CI 5.17 to 11.59), and total motility by 8.14 percentage points (95% CI 3.83 to 12.45). Morphology did not differ. Across the 10 studies reporting it, the mean pregnancy rate during treatment was 17 percent, with a range of 0 to 40 percent.

  The limit: Heterogeneity was high (I-squared 87 percent for concentration, 76 percent for motility) and the pooled comparison is before against during treatment rather than against placebo. Huijben M et al., Andrology, 2023.

• Retrospective multi-institutional comparison of 188 men on clomiphene citrate against 175 men on testosterone replacement, all with symptomatic hypogonadism. Polycythemia was present in 11.2 percent of the testosterone group against 1.7 percent of the clomiphene group (p=0.0003), and the difference held on logistic regression correcting for age, site, smoking history and pretreatment hematocrit. Mean hematocrit change was 3.0 percent on testosterone against 0.6 percent on clomiphene, on similar testosterone gains, 333.1 ng/dL on testosterone and 367.6 ng/dL on clomiphene.

  The limit: Retrospective, and the testosterone group was older (51.5 against 38 years) and treated for longer (19.6 against 9.2 months). Wheeler KM et al., Journal of Urology, 2017.

• Retrospective review of 400 men treated with clomiphene citrate for hypogonadism at two institutions between 2010 and 2018, of whom 120 were treated for more than three years (mean 51.93 months). Among the men treated more than three years, 88 percent reached eugonadism, 77 percent reported improved symptoms and 8 percent reported side effects. The most common in that group were mood changes in 5 men, blurred vision in 3 and breast tenderness in 2. Estradiol rose significantly on treatment.

  The limit: Retrospective and uncontrolled, at two centres, so it measures what happened to men who stayed on the drug rather than what the drug does against a comparator. Krzastek SC et al., Journal of Urology, 2019.

• Phase II randomized trial of oral enclomiphene citrate against 1 percent topical testosterone gel in men with secondary hypogonadism, registered as NCT01270841. Enclomiphene raised morning testosterone to levels similar to the gel while raising LH and FSH, and sperm counts were conserved.

  The limit: Phase II, sponsored by Repros Therapeutics, the company whose enclomiphene application was never approved. Wiehle RD et al., Fertility and Sterility, 2014.

Put together: clomiphene raised testosterone by about as much as testosterone replacement did in the retrospective comparison above, carried a much lower rate of the blood-thickening side effect in that same comparison, is associated with higher sperm concentration and motility during treatment in men being treated for infertility, and has not been through a large randomized placebo-controlled trial in male hypogonadism measuring hard long-term outcomes. That last clause is part of why it has no male indication, and it is the honest shape of the whole category. The enclomiphene evidence is stronger in design, two randomized trials against topical testosterone, and weaker in independence: the phase II trial above was run out of Repros Therapeutics, the company whose enclomiphene application was never approved, and its first author's affiliation on the paper is that company.

The side effects the label prints and the clinics summarise

The approved label carries an adverse-event table with a denominator of 8,029 women in the drug's clinical studies. Every percentage in it describes women, and two of its rows are anatomically inapplicable to men, so this page does not launder them into male rates. It prints the table with its denominator attached and lets you read it for what it is.

Events reported at greater than 1 percent in clinical studies, as printed on the Clomid label. The visual-symptoms row covers blurred vision, lights, floaters, waves, unspecified visual complaints, photophobia, diplopia, scotomata, phosphenes. The label puts an asterisk on its own denominator: “Includes 498 patients whose reports may have been duplicated in the event totals and could not be distinguished as such. Also, excludes 47 patients who did not report symptom data.”

The male-specific safety numbers come from the long-term series above: of the men treated longer than three years, 8 percent reported side effects, most commonly mood changes, blurred vision and breast tenderness, and estradiol rose significantly on treatment. That last point is the one to monitor. Clomiphene and enclomiphene both raise the whole signalling cascade, estradiol included, which is a plausible driver of the breast-tissue and mood complaints and a reason bloodwork is not optional. Testosterone side effects, with the same treatment.

Related

• Enclomiphene explained the isomer our roster actually sells, with its trials and its compounding caveat
• Testosterone cypionate the route all three of these are being weighed against
• TRT provider rankings the men's wing, scored and grade-labelled
• What TRT actually costs and cheapest TRT
• Testosterone side effects