Enclomiphene

Enclomiphene, also written enclomifene and known in development as Androxal or trans-clomiphene, is the (E)-isomer of clomifene citrate. It is a non-steroidal selective oestrogen receptor modulator (SERM) that acts on oestrogen receptors in the hypothalamus and pituitary. This page lists every brand of enclomiphene stocked at Free Muscle, compared on strength per capsule, capsules per pack and whether the batch has been assayed by an independent laboratory. It is sold for laboratory research to adults only.

What is enclomiphene?

Clomifene, the parent compound, is a roughly 60:40 mixture of two geometric isomers. Enclomiphene is the trans (E) isomer. The other, zuclomiphene, has a much longer half-life and is generally described as the more oestrogenic of the two.

The mechanism is antagonism of oestrogen receptors in the hypothalamus. Oestradiol normally feeds back to reduce the release of gonadotropin-releasing hormone, so blocking that signal allows luteinising hormone (LH) and follicle-stimulating hormone (FSH) to rise, which in turn drives testicular testosterone production. This is why enclomiphene was developed as a treatment for secondary hypogonadism in men, rather than as a replacement testosterone.

Enclomiphene citrate went through phase II and phase III clinical trials in the United States under Repros Therapeutics. A new drug application was filed in the United States and withdrawn in 2015 after the FDA raised concerns about the trial endpoints, and the marketing authorisation application in the European Union was later withdrawn. Enclomiphene is available as a prescription medicine in some countries, but it is not licensed by the MHRA in the UK, and it is not an authorised food supplement. Clomifene itself is a prescription-only medicine in the UK.

What the published research reports

Unlike most compounds sold in this category, enclomiphene has controlled human trial data. The findings below are reported neutrally, with their limitations.

• Pharmacokinetic and pharmacodynamic study (2013). A phase II randomised study in 44 men with secondary hypogonadism compared three enclomiphene doses with transdermal testosterone over six weeks. Mean morning testosterone in the highest enclomiphene group reached about 604 ng/dL against about 500 ng/dL with the gel, and only enclomiphene raised LH and FSH. Effects persisted for at least a week after stopping. Thyroid, cortisol and lipid values were not significantly changed. The sample was small and the study was short. Wiehle R, et al. Testosterone restoration by enclomiphene citrate in men with secondary hypogonadism: pharmacodynamics and pharmacokinetics. BJU Int. 2013;112(8):1188-1200. PMID: 23875626.
• Phase II trial against topical testosterone (2014). Oral enclomiphene citrate was compared with 1 per cent testosterone gel in men with secondary hypogonadism. Both raised morning serum testosterone to a similar degree. Enclomiphene raised LH and FSH and preserved sperm concentration, whereas the gel group showed suppressed spermatogenesis. Wiehle RD, et al. Enclomiphene citrate stimulates testosterone production while preventing oligospermia: a randomized phase II clinical trial comparing topical testosterone. Fertil Steril. 2014;102(3):720-727. PMID: 25044085.
• Phase III trials in overweight men (2016). Two 16-week phase III studies in overweight men aged 18 to 60 with secondary hypogonadism again found that enclomiphene raised testosterone, LH and FSH while sperm concentration was maintained, and that testosterone gel lowered LH, FSH and sperm concentration. Despite these results the US application was withdrawn after the FDA questioned whether the chosen endpoints showed a clinical benefit to patients. Kim ED, et al. Oral enclomiphene citrate raises testosterone and preserves sperm counts in obese hypogonadal men, unlike topical testosterone: restoration instead of replacement. BJU Int. 2016;117(4):677-685. PMID: 26496621.

Across these trials the reported adverse events were generally mild, but the studies were of short duration, in clinically diagnosed patients under medical monitoring, and none of them examined long-term effects, effects in men with normal hormone levels, or effects in women. A SERM acts directly on the endocrine axis, and the trials themselves relied on repeated blood tests. None of the above is a claim about any product on this page.

Brands of enclomiphene we stock

• Free Muscle Enclomiphene 25 mg, 60 capsules. Our own brand, 25 mg per capsule, 60 capsules per pack, giving 1,500 mg of enclomiphene per pack. Every Free Muscle batch is assayed by Janoshik Analytical for identity and purity, and the certificate for the batch you receive is available by email on request. View Free Muscle Enclomiphene 25 mg.
• Yakka Strength Enclomiphene, 60 capsules. A third-party brand in capsule form, 60 capsules per pack. The per-capsule strength is not stated in our listing data, so check the label detail on the product page before comparing. A batch certificate is shown only where Yakka Strength supplies one for the batch we hold. View Yakka Strength Enclomiphene.

How to compare them

Multiply the strength per capsule by the number of capsules to get total milligrams per pack, then divide the price by that figure for a cost per milligram. Two packs of 60 capsules are not equivalent if one is 12.5 mg and the other 25 mg per capsule. Where a strength is not printed on the listing, treat the pack as unquantified until you have seen the certificate. Finally, check who tested the batch, what method they used and whether the batch number on the certificate matches the pack.

Batch testing and certificates of analysis

A certificate of analysis (COA) for a research compound reports two things: identity, meaning that the material is actually enclomiphene and not clomifene or something else entirely, and purity, meaning what proportion of the sample is that compound, usually by HPLC. A good certificate names the laboratory, the method, the batch number, the date and the measured result. Every Free Muscle batch is tested by Janoshik Analytical, an independent laboratory that we neither own nor control. To request the certificate for your batch, email us with the batch number printed on the pack and we will send it.

A generic PDF with no batch number, no date or no named laboratory is not a batch certificate. It describes one sample at one point in time, not necessarily the material in your hands. For other brands we show a certificate only when the manufacturer has supplied one for the batch we hold. We explain what to look for on our lab testing page.

Legal status in the UK

Enclomiphene is not a licensed medicine in the UK. The MHRA has not granted it a marketing authorisation, and it has never been assessed as a food supplement, so it cannot be sold for consumption. It is supplied by Free Muscle for laboratory research to adults aged 18 or over. Its parent compound clomifene is a prescription-only medicine, and some overseas markets treat enclomiphene the same way.

For sport, selective oestrogen receptor modulators are listed under section S4 of the WADA Prohibited List, hormone and metabolic modulators, and are prohibited at all times, in and out of competition. Enclomiphene falls within that class. It is detectable in anti-doping testing. Anyone subject to testing should treat it as prohibited. Our article on why post-cycle therapy is discussed covers the wider background to this class of compound.

Storage and handling

Keep the container tightly sealed in a cool, dry place away from direct light and heat. Do not decant into unlabelled containers, keep the batch number with the material, and handle it in line with good laboratory practice. Keep out of the reach of children and animals.

Delivery and returns

Free Muscle is a UK company, FreeMuscle LTD, based in Scunthorpe. Every order ships with free tracked UK delivery in plain packaging. Orders placed before 2pm Monday to Friday are processed the same working day. EU delivery takes 3 to 7 working days. Unopened items can be returned within 30 days. Customers must be 18 or over. See shipping and our guarantee for the full terms.

Related reading

• Why Post-Cycle Therapy (PCT) Matters
• How to Read a Certificate of Analysis (COA)
• What Is Janoshik Analytical? Third-Party Testing Explained
• Price per milligram: the only honest way to compare
• What Are SARMs? The 2026 Research Guide

Related collections: PCT blends, RAD-140, SARMs, Yakka Strength.

All products on this page are supplied for laboratory research use only. Enclomiphene is not a licensed medicine in the UK and has not been evaluated by the MHRA, EMA or FDA. It is not a food supplement and is not for human consumption. You must be 18 or over to order. Nothing on this page is medical, dosing or protocol advice.

Research guides

• Enclomiphene vs clomiphene (clomifene): what the trials report
• What is in a PCT blend? Ingredients, evidence and UK status