Enclomiphene Citrate Self-Injection Technique: Why This Oral Drug Does Not Require Injections

Why People Search for an Injection Technique

Enclomiphene is often discussed alongside testosterone replacement, which can make it sound like an injectable. Every enclomiphene dose studied was taken by mouth [1][2]. The two approaches also act differently on the same hormone axis: in two 16-week phase 3 studies, LH and FSH rose in the men given enclomiphene and fell in the men given testosterone gel [7]. Enclomiphene signals the pituitary to prompt the testes to make more of their own testosterone; replacement testosterone supplies the hormone itself.

What Enclomiphene Is

Enclomiphene is an oral selective estrogen receptor modulator (SERM) [3]. It blocks estrogen receptors in the pituitary. Estrogen normally suppresses the pituitary-testis axis, so blocking those receptors makes the pituitary release more LH and FSH, which tells the testes to make more testosterone and to keep making sperm [3]. That mechanism fits secondary (hypogonadotropic) hypogonadism, where the testes are healthy but under-stimulated. It would not be expected to work in primary hypogonadism, where the testes themselves are failing [3].

Enclomiphene is also not the same drug as clomiphene. Clomiphene citrate is a mixture of two isomers, enclomiphene (trans) and zuclomiphene (cis), and FDA states that the USP monograph gives enclomiphene content of clomiphene as 50 to 70 percent [3]. Zuclomiphene is the more estrogenic of the two and enclomiphene the more anti-estrogenic, pro-gonadotropic one [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 in normal volunteers [9].

How Enclomiphene Is Taken

Orally, once a day. There is no FDA-approved dose because there is no approved product [3]. Doses that have been studied are 6.25, 12.5 and 25 mg once daily by mouth in a six-week phase 2 dose-finding trial [1]. The phase 3 protocols used 12.5 mg once daily, with up-titration to 25 mg daily at week 6 if morning testosterone stayed below 300 ng/dL [2]. The nominator that asked FDA to allow compounding proposed capsules or tablets of 12.5, 25 and 50 mg [2].

Oral enclomiphene is absorbed quickly, with a peak about 2 to 3 hours after a dose and a half-life of roughly 10 hours; the main metabolite is 4-hydroxy enclomiphene and excretion is mainly in the feces [3].

Enclomiphene vs Testosterone Gel: What the Trials Show

The clearest head-to-head data come from two parallel randomized, double-blind, double-dummy, placebo-controlled phase 3 studies published in BJU International in 2016 by Kim and colleagues. They enrolled overweight men aged 18 to 60 with secondary hypogonadism and morning testosterone of 300 ng/dL or lower, and compared two doses of oral enclomiphene with AndroGel 1.62 percent over 16 weeks [7]. Total testosterone rose in all treatment groups [7]. LH and FSH rose with enclomiphene and fell with testosterone gel [7]. Sperm concentration stayed in the normal range on enclomiphene, while there was a marked reduction in spermatogenesis on testosterone gel [7].

Earlier and smaller studies pointed the same way. A randomized phase 2 trial found that enclomiphene raised morning testosterone, estradiol and LH to levels similar to 1 percent testosterone gel, raised FSH and LH, and preserved sperm counts [10]. A 12-man phase 2b study in men who had been using topical testosterone found 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 [11].

Preserving sperm is not the same as never affecting it. In the phase 3 study ZA-301, sperm concentration fell by 50 percent or more in 14.2 percent of men on enclomiphene versus 2.6 percent on placebo [2]. In ZA-302, the figures were 14.2 percent versus 4.3 percent [6].

Side Effects and Safety Concerns

The most frequent side effects in the phase 3 and EMA data were headache, hot flushes, nausea and muscle spasm, and reasons for stopping included blurred vision, muscle spasm, headache and aggression [6]. In ZA-302, over 12 weeks, 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 [6].

FDA listed the safety concerns it had identified 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 [3]. EMA noted a slightly higher rate of cardiac and thromboembolic events than with testosterone, and cataracts in nonclinical studies, and wanted ocular monitoring [3].

Regulatory Status: Not Approved, Under Evaluation

Enclomiphene is not FDA-approved. FDA's own 2022 advisory-committee presentation states that no FDA-approved drugs contain enclomiphene as an active ingredient, and it is not approved in the EU either [3]. The sponsor, Repros Therapeutics, submitted an application for Androxal in secondary hypogonadism; in 2015 the company announced a complete response letter, which as FDA summarizes it said the phase 3 designs were not adequate to demonstrate clinical benefit and raised concerns about entry criteria, titration and bioanalytical method validation [3]. EMA's committee adopted a negative opinion on 25 January 2018 for EnCyzix, citing studies that showed higher testosterone but did not look at whether symptoms improved, and a risk of venous thromboembolism, based on 4 main studies in 588 patients [4]. A 2026 British Society of Sexual Medicine position statement notes that the manufacturer discontinued development in 2021 and advises use only by experienced clinicians in specialist or research settings [8].

On compounding, FDA's list updated 14 May 2026 places enclomiphene citrate in Category 1, bulk drug substances under evaluation. 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; that is an enforcement-discretion policy, not an approval and not a finding that the product is safe or effective [5]. Compounded enclomiphene products are not FDA-approved and have not been reviewed by FDA for safety, effectiveness or quality [13].