What Is Enclomiphene? Half-Life, Dosing Math & How to Track It

What enclomiphene is and how it works

Clomiphene citrate is a roughly 62:38 mix of two stereoisomers: enclomiphene (trans) and zuclomiphene (cis). Enclomiphene is the isomer doing almost all of the useful work — it blocks estrogen receptors at the hypothalamus, drives up GnRH pulse frequency, and increases pituitary LH and FSH output, which in turn raises the testes’ own testosterone production.

Isolating enclomiphene on its own removes zuclomiphene from the equation entirely — no lingering weeks-long estrogenic tail, in theory a cleaner side-effect profile, and a much shorter, more predictable half-life. The trade-off is regulatory: enclomiphene went through clinical trials under the investigational name Androxal but has not been approved by the FDA as a standalone branded drug, so it’s currently available mainly through compounding pharmacies and prescribed off-label.

The clinical use case mirrors clomiphene’s: raising endogenous testosterone in men with secondary hypogonadism, or supporting recovery of natural production after a course of exogenous testosterone or anabolic-androgenic steroids — without the fertility suppression that injectable testosterone causes.

Dosing math without a syringe

Enclomiphene is an oral capsule, so there’s no concentration or reconstitution math — but because it’s compounded rather than mass-produced, it typically ships in whatever fixed strengths a given pharmacy offers, most commonly 12.5 mg or 25 mg capsules, rather than a larger tablet you split down.

Because the capsule strength is fixed by the compounding pharmacy, switching strengths (say from 12.5 mg to 25 mg) means a new prescription rather than splitting what you have — worth planning around rather than discovering at refill time.

With a fixed-strength capsule, the only variable you control is frequency — logging each dose against the calendar is what keeps a weekly total accurate, especially on an EOD schedule where it’s easy to lose count.

Half-life & what it means for frequency

Enclomiphene’s half-life — roughly 10 hours — is short compared to a weekly injectable, but long enough relative to its once-daily dosing that levels don’t swing as dramatically as the number alone might suggest. Studies supporting once-daily dosing found the LH/FSH-raising effect held up across the day even as plasma levels declined, which is common for drugs that act at a receptor rather than needing to stay at a constant blood concentration.

That’s the practical upside of isolating enclomiphene from clomiphene: no zuclomiphene means no multi-week clearance tail, so the whole drug — effect and clearance — moves on roughly the same daily rhythm as the dose.

What to track & side effects

The relevant labs mirror clomiphene’s: LH, FSH, total and free testosterone, and estradiol, since raising endogenous testosterone also raises the substrate available for aromatization. If fertility is part of the goal, semen parameters over time complete the picture.

Reported side effects are generally milder than clomiphene’s, consistent with dropping the estrogenic zuclomiphene component — some mood changes and hot flashes are still reported, and the same visual-disturbance warning that applies to clomiphene applies here too: stop and contact a prescriber if blurred vision, flashes, or spots occur.

Frequently asked questions