Enclomiphene Citrate Dosing for Young Adults (18 to 29): Evidence, Protocols, and Monitoring

Is there a dose of enclomiphene made for men aged 18 to 29?

The phase 3 trials enrolled men aged 18 to 60 with secondary hypogonadism and morning testosterone of 300 ng/dL or lower [3][6]. The trials included adults as young as 18 and report results for the enrolled group [3][6].

Enclomiphene is an oral selective estrogen receptor modulator. It blocks estrogen receptors in the pituitary, so the pituitary releases more LH and FSH, which tells the testes to make more testosterone and keep producing sperm [1]. That mechanism fits secondary hypogonadism, where the testes are healthy but under-stimulated, and would not be expected to work when the testes themselves have failed [1].

What doses were actually tested?

Three once-daily oral doses have been studied: 6.25, 12.5 and 25 mg. They were compared in a 6-week randomized single-blind phase 2 trial that enrolled 48 men and included a transdermal testosterone gel arm; testosterone and LH rose with enclomiphene [2].

The two 12-week phase 3 trials used 12.5 mg once daily, with up-titration to 25 mg at week 6 if morning testosterone was still below 300 ng/dL [3]. The nomination that proposed enclomiphene for compounding listed capsule or tablet strengths of 12.5, 25 and 50 mg [3]; 25 mg is the highest studied dose, and 50 mg is a proposed product strength rather than a tested regimen.

One pharmacokinetic detail matters for timing: oral enclomiphene reaches peak blood levels 2 to 3 hours after a dose and has a half-life of about 10 hours [1].

What the phase 3 results looked like

Both trials were randomized, double-blind and placebo-controlled, and both required morning testosterone of 300 ng/dL or lower to enroll [3][7]. The pre-set success bar was an average 24-hour testosterone between 300 and 1040 ng/dL, with the lower confidence limit at 67% or better; FDA did not require a placebo comparison for that endpoint [3].

In ZA-301, 151 overweight men, 78.8% of those on enclomiphene reached that range (95% CI 70.3 to 85.3, n=113) [3]. In ZA-302, 181 men, the figure was 81.3% (95% CI 73.9 to 87.0, n=134) [7].

Hormone levels were the endpoint. The trials did not report whether symptoms improved, and FDA's 2018 guidance on secondary hypogonadism notes that it is unclear whether raising testosterone in this population produces clinical benefit and that semen-parameter changes alone are not enough to establish efficacy [1].

What the trials tracked

The trials tracked testosterone, LH, FSH and sperm concentration [2][3][7][6]. The 2026 British Society of Sexual Medicine position statement says enclomiphene should be used only by experienced clinicians in specialist or research settings because long-term efficacy and safety data are lacking [8].

Estradiol rose along with testosterone on enclomiphene, at levels similar to a 1% testosterone gel [9].

Regulators listed the safety concerns that came out of the published trials, adverse event reports and EMA's review: cardiac and thromboembolic events, including pulmonary embolism and deep vein thrombosis in a safety study; raised estradiol; raised PSA; raised hematocrit; and no long-term safety data [1]. EMA, whose committee recommended refusing the marketing application in 2018, noted a slightly higher rate of cardiac and thromboembolic events than with testosterone and asked for ocular monitoring because cataracts appeared in nonclinical studies [1].

Sperm and fertility

In the two phase 3 studies that compared enclomiphene with AndroGel 1.62% over 16 weeks in men aged 18 to 60, total testosterone rose in all treatment groups, LH and FSH rose with enclomiphene and fell with the gel, and sperm concentration stayed in the normal range on enclomiphene while there was a marked reduction in spermatogenesis on the gel [6].

Sperm is not untouched, though. In ZA-301, sperm concentration fell by 50% or more in 14.2% of men on enclomiphene versus 2.6% on placebo [3]; in ZA-302 the figures were 14.2% versus 4.3% [7].

A smaller 12-man study followed men who had been using topical testosterone. Sperm counts rose in 7 of 7 men on enclomiphene at 3 months, while the gel did not raise counts above 20 million/mL in any of 5 men at 3 months [10].

Side effects reported in the trials

In ZA-302, headache was reported by 7 of 112 men on 12.5 mg versus 1 of 47 on placebo, and nausea by 4 of 112 versus 3 of 47 [7]. Across the phase 3 programme and EMA's review, the most frequent were headache, hot flushes, nausea and muscle spasm; reasons men stopped included blurred vision, muscle spasm, headache and aggression [7].

Visual symptoms appear on the clomiphene label. For clomiphene, the label reports blurred vision, spots and flashes that are usually reversible but may rarely persist [11]. That warning has not been established for enclomiphene alone; blurred vision was nevertheless reported as a reason some trial participants stopped enclomiphene [11][7].

Approval status, compounding and sport

FDA's own advisory-committee presentation from June 2022 states that no FDA-approved drugs contain enclomiphene as an active ingredient [1]. In 2015 the sponsor, Repros Therapeutics, announced a complete response letter from FDA for Androxal in secondary hypogonadism; as FDA summarized it, the phase 3 design was not adequate to demonstrate clinical benefit, and there were concerns about study entry criteria, titration and bioanalytical method validation [1]. EMA's committee adopted a negative opinion on 25 January 2018 for EnCyzix, based on 4 main studies in 588 patients: testosterone rose, but the studies did not examine whether symptoms improved, and there was a risk of venous thromboembolism [5].

On compounding, FDA's list updated 14 May 2026 places enclomiphene citrate in Category 1, bulk drug substances under evaluation, and FDA says it does not intend to act against a compounder using a Category 1 substance if the conditions in its guidance are met, which is an enforcement-discretion policy rather than an approval [12]. In 2022 FDA proposed not adding it to the allowed list, and the advisory committee voted 4 yes, 8 no [4]. Compounded enclomiphene products have not been reviewed by FDA for safety, effectiveness or quality [13].

For athletes, WADA's 2026 Prohibited List bans anti-estrogenic substances and SERMs at all times and names clomifene [14]. Enclomiphene is not named separately, but the list is written as including, but not limited to, and enclomiphene is an isomer of clomifene [14].

Enclomiphene versus clomiphene

Clomiphene citrate is a mixture of two isomers, enclomiphene (trans) and zuclomiphene (cis); FDA cites a USP monograph figure of 50 to 70 percent enclomiphene content [1]. Zuclomiphene is the more estrogenic of the two [8]. The Clomid label notes that zuclomiphene has a longer half-life than enclomiphene and that detectable zuclomiphene levels persisted for longer than a month in single-dose studies [11].

Clomiphene itself is FDA-approved only for ovulatory dysfunction in women who want to become pregnant. Its label has no male indication, states that there are no adequate or well-controlled studies demonstrating effectiveness in male infertility, and notes that testicular tumours and gynecomastia have been reported in men using clomiphene, with cause and effect not established [11].