Enclomiphene Citrate Adult (30-49) Dosing: Complete Clinical Guide

Does enclomiphene have an approved adult dose?

No. FDA's advisory committee material from June 2022 states that no FDA-approved drugs contain enclomiphene as an active ingredient [1]. The sponsor's new drug application for Androxal in secondary hypogonadism in fertile men ended with a complete response letter in 2015; as FDA summarised it, the phase 3 study design was not adequate to demonstrate clinical benefit, and the agency raised concerns about entry criteria, titration and bioanalytical method validation [1]. In Europe, EMA's committee adopted a negative opinion on 25 January 2018 recommending refusal of marketing authorisation for EnCyzix (enclomifene) for hypogonadotropic hypogonadism in overweight men [5].

With no approval there is no label dose, no approved titration step and no approved monitoring schedule. What follows is what the trials did.

What doses were actually tested?

Phase 2 dose-finding. A randomized, single-blind, two-center phase 2 study gave enclomiphene 6.25, 12.5 or 25 mg once daily, or transdermal testosterone gel, for 6 weeks. Forty-eight men were enrolled and 44 completed; total testosterone and LH rose with enclomiphene [2].

Phase 3 protocols. Men received 12.5 mg once daily, with up-titration to 25 mg daily at week 6 if morning testosterone stayed below 300 ng/dL [3].

Phase 3 arms. ZA-301 randomized 151 men to 12.5 mg, 25 mg or placebo for 12 weeks [3]. ZA-302 randomized 181 men: 112 to 12.5 mg, 22 to 25 mg and 47 to placebo [6]. ZA-304 and ZA-305 compared two enclomiphene doses with testosterone gel 1.62% over 16 weeks [4].

What the phase 3 results showed, and what they did not measure

In ZA-301, 78.8% of men on enclomiphene (95% CI 70.3 to 85.3, n=113) reached an average 24-hour testosterone in the normal range of 300 to 1040 ng/dL. The pre-set success bar was a lower confidence limit of at least 67%, and FDA did not require a placebo comparison for this endpoint [3]. Sperm concentration fell by 50% or more in 14.2% of men on enclomiphene versus 2.6% on placebo [3].

In ZA-302, 81.3% (95% CI 73.9 to 87.0, n=134) reached the normal range, and sperm concentration fell by 50% or more in 14.2% versus 4.3% on placebo [6]. Results for both studies are posted on ClinicalTrials.gov [3][6].

The endpoints were hormone levels, sperm counts and safety. Symptom scores and quality of life were not the outcomes measured, and both regulators treated that as the central gap. FDA's May 2018 guidance on secondary hypogonadism, as described by FDA in 2022, says it is unclear whether raising testosterone in this population produces clinical benefit, and that trials should show meaningful improvement in at least one symptom or sign [1]. EMA's refusal reasons were that the studies showed higher testosterone but did not examine whether symptoms improved, and that there is a risk of venous thromboembolism; that review covered 4 main studies in 588 patients [5].

Does the 30-49 age bracket change the dose?

The phase 3 entry criteria were overweight men aged 18 to 60 with morning testosterone below 300 ng/dL and normal sperm concentration [3]. ZA-304 and ZA-305 enrolled overweight men aged 18 to 60 with morning testosterone of 300 ng/dL or lower [4]. The only dose change in the protocols was the week 6 step-up based on morning testosterone [3], so a 35-year-old and a 45-year-old would have followed the same schedule. These were mixed-age groups, and the results are not split by decade.

Side effects reported at these doses

Headache, hot flushes, nausea and muscle spasm were the most frequent side effects [6]. In ZA-302, headache was reported by 7 of 112 men on 12.5 mg and 1 of 47 on placebo; nausea by 4 of 112 and 3 of 47 [6]. Reasons for stopping included blurred vision, muscle spasm, headache and aggression [6].

FDA listed these concerns in 2022 from 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 noted a slightly higher rate of cardiac and thromboembolic events than with testosterone, and cataracts in nonclinical studies, and wanted ocular monitoring [1].

The clomiphene label is not an enclomiphene label

Clomiphene citrate (Clomid) is FDA-approved only for ovulatory dysfunction in women who want to become pregnant [9]. The label has no male indication, states that there are no adequate or well-controlled studies demonstrating effectiveness in male infertility, and notes that testicular tumors and gynecomastia have been reported in men using clomiphene, with cause and effect not known [9]. Its contraindications include liver disease or a history of liver dysfunction, uncontrolled thyroid or adrenal dysfunction, pituitary tumour and pregnancy [9].

The label's visual-symptom warning describes blurring, spots or flashes (scintillating scotomata) that are usually reversible but may be irreversible, especially at higher dose or longer duration [9]. Visual symptoms were reported in 1.5% of 8,029 patients in clomiphene's clinical studies, a population treated for ovulation [9]. That warning is written for the mixture of isomers, not for enclomiphene alone [1][9].

On the isomer question: clomiphene is a mixture of enclomiphene (trans) and zuclomiphene (cis), and per FDA the USP monograph gives enclomiphene content of clomiphene as 50 to 70 percent [1]. Zuclomiphene is the more estrogenic of the two and enclomiphene the more anti-estrogenic, pro-gonadotropic isomer [7]. On that basis a milligram of clomiphene contains less than a milligram of enclomiphene.

Enclomiphene itself is absorbed quickly, peaks 2 to 3 hours after a dose, has a half-life of about 10 hours and is excreted mainly in faeces [1]. The clomiphene label notes that zuclomiphene has the longer half-life, with detectable levels persisting more than a month in single-dose studies [9].

Fertility at these doses

In the phase 3 comparison with testosterone gel, sperm concentration stayed in the normal range on enclomiphene while there was a marked reduction in spermatogenesis on the gel [4]. In the phase 2 trial, enclomiphene raised morning testosterone, estradiol and LH to levels similar to 1% testosterone gel, raised FSH and LH, and preserved sperm counts [10]. In the 12-man phase 2b study, sperm counts rose in 7 of 7 men on enclomiphene at 3 months, while gel did not raise counts above 20 million/mL in any of 5 men at 3 months [11].

In ZA-301 and ZA-302, sperm concentration fell by 50% or more in 14.2% of men receiving enclomiphene, compared with 2.6% and 4.3% on placebo [3][6]. In the 12-man study, testosterone fell back to pre-treatment values one month after stopping [11].

Compounding and legal status

FDA's list (updated May 14, 2026) places enclomiphene citrate in Category 1, 'Bulk Drug Substances Under Evaluation'. That is an enforcement-discretion policy under stated conditions, not FDA approval and not a finding that the product is safe or effective [12]. FDA says it does not intend to take action against a compounder using a Category 1 substance if the conditions in its guidance are met [12]. Enclomiphene does not appear on FDA's Category 2 list of bulk substances that may present significant safety risks [13].

At the 8 June 2022 meeting of FDA's Pharmacy Compounding Advisory Committee, FDA proposed that enclomiphene citrate not be added to the list of allowed bulk substances, and the committee voted 4 yes, 8 no, 0 abstain [14].

The 2026 British Society of Sexual Medicine position statement notes that enclomiphene is not approved by FDA or EMA, that its manufacturer discontinued development in 2021, and advises use only by experienced clinicians in specialist or research settings, given the lack of long-term efficacy and safety data [7].