Enclomiphene
Enclomiphene citrate
Enclomiphene is the pure antagonist isomer of clomiphene. It raises endogenous testosterone by blocking estrogen feedback in the brain — with fewer of the mood and libido side effects associated with clomiphene's zuclomiphene contaminant.
Selective estrogen receptor modulator (SERM) — pure trans-isomer of clomiphenePrescription requiredEvidence B
⚠ Not medical advice.Not medical advice. This page is educational. Discuss with your physician before starting, changing, or stopping any medication.
Why it matters
Clomiphene works, but it carries a passenger: zuclomiphene, a weak estrogen agonist that accumulates over weeks and is the suspected culprit behind the mood flattening and libido drops some men experience. Enclomiphene is the trans-isomer — pure antagonist, no agonist baggage. Wiehle and colleagues demonstrated in their 2014 trial that enclomiphene at 12.5–25 mg daily raised serum testosterone into the mid-normal range while preserving (and often improving) LH, FSH, and sperm parameters. The Kim and Wiehle work directly compared enclomiphene to testosterone gel and found comparable T elevation with maintained spermatogenesis. The FDA rejected the Androxal NDA twice (2015, 2016) — not on safety grounds, but on issues with the chosen comparator and primary endpoint design. The drug remains off-label and only available via compounding. For men who tried clomiphene and felt worse despite good labs, enclomiphene often resolves the issue. Evidence grade: B — mechanism is solid, short-term trial data is consistent, long-term outcomes (>1 year) are sparse.
Dosing
Label dose
No FDA-approved label dose (Androxal NDAs were rejected in 2015 and 2016)
Off-label / biohacker dose
12.5–25 mg daily, or 12.5 mg every other day; most clinicians start at 12.5 mg daily
Titration: Start low. The absence of zuclomiphene means levels stabilize within ~1 week. Recheck total T, free T, estradiol, LH at week 4–6.
When to take: Morning, daily
Side effects & warnings
Common
- Headache
- Mild nausea
- Mild mood changes (generally less than clomiphene)
- Hot flashes
Uncommon but serious
- Visual disturbances
- Reduced libido (rare)
Serious warnings
Not FDA-approved — all use is off-label and most product is from compounding pharmacies, with variable quality. The Androxal NDA was rejected by the FDA twice (2015, 2016) over study design and efficacy data — not safety. Long-term data beyond 6 months is limited.
Biomarkers affected
free testosterone
increaseTracks with total T rise; SHBG response varies.
Evidence: moderate
shbg
variableLimited data; some men see modest changes, mechanism via raised estrogen signaling at liver.
Evidence: weak
total testosterone
increaseReliable mid-normal range elevation in secondary hypogonadism in trial data.
Evidence: strong
Monitoring
Total T, free T, estradiol, LH, FSH, SHBG at baseline and at 6 weeks
The honest risk picture
## Realistic risks of enclomiphene
**Not FDA-approved:** All product is compounded. Potency, purity, and bioavailability vary by pharmacy. Choose a reputable compounder with quality controls.
**Limited long-term data:** Most trials are ≤6 months. Beyond a year, safety and durability of effect are inferred but not robustly demonstrated.
**Estradiol still rises:** Because LH and intratesticular T go up, estradiol typically follows. Some men still need an AI adjustment.
**Visual disturbances:** Same SERM-class risk as clomiphene, though apparently less common with enclomiphene in available data.
**Mood effects:** Most men do better than on clomiphene, but a subset still experience flat mood or anxiety — likely from estradiol shifts or individual SERM response.
**Insurance:** Rarely covered, since it is off-label compounded.
**Only works for secondary hypogonadism:** Like clomiphene, enclomiphene requires functional testes. Primary testicular failure will not respond.
**Stopping is straightforward:** Unlike TRT, enclomiphene does not suppress the HPG axis — discontinuation simply returns you to baseline within days to weeks.
Practical context
Cost (US, retail)
$60/mo
Legality
Not FDA-approved as a finished product in the US. Available via compounding pharmacies on prescription. Quality control varies by pharmacy.
Interactions
false
FAQ
How is enclomiphene different from clomiphene?+
Clomiphene is a 50/50 mix of enclomiphene (antagonist) and zuclomiphene (weak agonist). Zuclomiphene accumulates over weeks and is implicated in mood/libido side effects. Enclomiphene is the purified active half — cleaner profile in most men.
Is enclomiphene FDA-approved?+
No. The Androxal NDA was rejected in 2015 and 2016. All current use is off-label via compounding pharmacies. Quality varies.
Does enclomiphene preserve fertility?+
Yes — by raising LH and FSH, it stimulates the testes directly. Sperm parameters typically improve or remain stable, unlike on TRT.
References (4)+
- Enclomiphene Citrate Stimulates Testicular Steroidogenesis in Men with Secondary Hypogonadism (Wiehle et al., 2014).
- Enclomiphene Citrate vs Testosterone Gel (Kim & Yumchak, 2016 / Wiehle et al. BJU Int).
- Long-term Effects of Enclomiphene on Sperm and Hormone Parameters.
- FDA Complete Response Letter on Androxal (Repros Therapeutics, 2015–2016).
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