This Fertility Drug Raises Testosterone 274 ng/dL in Men, But 75% Experience a Shocking Side Effect Doctors Rarely Monitor

What if there’s a compound more divisive than Two-Face himself?

Today, the spotlight falls on enclomiphene—a drug with a genuine split personality that’s quietly become one of the most prescribed men’s health medications in America.

On one side sits a fertility tool backed by decades of data, the responsible Harvey Dent half. On the other lurks a controversial low-testosterone treatment that telehealth companies have dispensed to millions of men, delivering results ranging from life-changing to utterly underwhelming.

In a recent video, Dr. Alex, a board-certified urologist and fellowship-trained men’s health specialist, dissected this pharmaceutical enigma with the kind of brutal honesty rarely found in wellness circles.

The Origin Story: From Failed Contraceptive to Fertility Champion

Understanding enclomiphene requires rewinding to its parent compound, clomiphene citrate—better known as Clomid.

Synthesized in 1956 by chemist Frank Palopoli at the William S. Merrell Company, the drug was initially explored as a potential contraceptive. That experiment flopped spectacularly.

Instead of preventing pregnancy, clomiphene induced ovulation in women. The FDA approved it in 1967 for ovulatory dysfunction, cementing its role in assisted reproduction.

But here’s what almost nobody realizes: Clomid isn’t one drug—it’s two drugs fused together.

Clomiphene citrate consists of two geometric isomers with identical atoms arranged in different configurations. The marketed mixture contains roughly 38% zuclomiphene (the cis isomer) and 62% enclomiphene (the trans isomer).

These isomers operate on opposing teams. Enclomiphene blocks estrogen receptors in the brain, driving testosterone production. Zuclomiphene, conversely, activates those same receptors and lingers in the system with a significantly longer half-life.

Think of this as like having one foot on the gas and one foot on the brake.

For decades, every man taking Clomid swallowed both isomers simultaneously—the accelerator and the anchor.

How the Mechanism Actually Works

The elegance of clomiphene’s mechanism lies in its deceptive simplicity.

By blocking estrogen receptors in the hypothalamus and pituitary gland, the drug tricks the brain into believing estrogen levels are inadequate. The brain responds by pumping out luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

In women, this hormonal surge triggers ovulation. In men, LH commands Leydig cells to manufacture testosterone, while FSH plus intratesticular testosterone supports sperm production.

The result? Higher testosterone while preserving fertility.

This stands in stark contrast to traditional testosterone replacement therapy (TRT), which operates as a shutdown mechanism. External testosterone signals the brain that hormone levels are sufficient, causing LH and FSH to plummet. Testicular function crashes, sperm production vanishes, and testicular atrophy follows.

Clomiphene and enclomiphene flip this script entirely—revving the body’s own engine instead of replacing it with an external source.

The FDA Rejection That Changed Everything

Repros Therapeutics recognized the opportunity and developed isolated enclomiphene under the brand names Androxal (US) and Enclisix (Europe), targeting secondary hypogonadism in overweight men concerned about fertility.

Clinical trials demonstrated the expected outcomes: enclomiphene elevated testosterone into normal ranges, increased LH and FSH, and maintained sperm counts. Testosterone gel comparisons showed the opposite—raised testosterone but devastated gonadotropins and sperm production.

Mechanistically, enclomiphene represented a clean victory.

Then came December 2015 and the FDA’s complete response letter—regulatory language for outright rejection.

The agency’s objection wasn’t that enclomiphene failed to raise testosterone. The problem centered on whether elevating lab values translated into measurable clinical benefit for symptom improvement.

The drug failed to come to market not because it didn’t raise testosterone, but because nobody could convince regulators that the symptom benefit was real.

Repros never conducted the additional trial the FDA demanded. Allergan acquired the company in 2017, and the program stalled. The European Medicines Agency refused authorization in January 2018 on similar grounds.

Today, enclomiphene holds zero regulatory approvals anywhere globally.

The Telehealth Explosion Nobody Saw Coming

Without FDA approval, enclomiphene can’t be dispensed through traditional pharmacies. The only access point? Compounding pharmacies.

This regulatory loophole became the foundation for an entire industry.

For years, men seeking endogenous testosterone boosting relied on generic Clomid from commercial pharmacies—cheap, available, and straightforward despite off-label use. Then supply disruptions struck.

A massive Clomid shortage hit in February 2019. In September 2022, major manufacturer Par discontinued its clomiphene tablets entirely. Generic supply became unreliable.

Prescribers pivoted to enclomiphene through compounding pharmacies—theoretically the cleaner isomer and, critically, actually available.

Then economics poured gasoline on the fire.

Telehealth operations identified enclomiphene as nearly perfect for their business model:

• Raises testosterone reliably
• Remarkably safe safety profile
• Preserves fertility
• Not a controlled substance

Unlike Schedule III testosterone, which requires DEA paperwork, dual-factor authentication, and pharmacy scrutiny, enclomiphene can be shipped to all 50 states with minimal regulatory friction.

The incentive structure practically engineered its explosion.

The Harvey Dent Half: Where Enclomiphene Actually Shines

As a fertility-adjacent intervention, enclomiphene genuinely earns its reputation.

A 2023 systematic review and meta-analysis examining male infertility found clomiphene increased sperm concentration and motility. Across 10 studies reporting pregnancy outcomes, the mean pregnancy rate during treatment reached approximately 17%—though ranges varied wildly from 0% to 40% depending on patient populations.

A separate meta-analysis confirmed sperm concentration improvements versus placebo or no treatment.

Enclomiphene-specific data reinforces this fertility-sparing narrative. Phase II and III trials consistently demonstrated testosterone elevation while maintaining sperm concentration—the opposite of topical testosterone gel, which demolished sperm counts.

But timing matters enormously.

A 2023 cohort tracking treatment progression found testosterone rises quickly, but sperm concentration didn’t show significant improvement until approximately nine months into therapy.

Most studies—and impatient patients—bail at three to four months. Abandoning treatment at 12 weeks because semen analysis appears unchanged means walking out during the opening credits.

The honest assessment? Strong evidence supports improved fertility parameters and preservation. Evidence for directly manufacturing pregnancies remains considerably weaker.

The Estrogenic Shadow and Desmosterol Debate

Even the fertility-focused Harvey Dent half carries blemishes, most traceable to estrogen and persistent zuclomiphene.

Because the entire hormonal axis revs upward, estradiol frequently rises alongside testosterone. Zuclomiphene contributes additional estrogenic activity that refuses to vacate receptors.

Some men experience this as moodiness, nipple sensitivity, or a vaguely “off” sensation despite perfect testosterone numbers on paper.

Then there’s desmosterol—the molecule one biochemical step before cholesterol synthesis completion.

Clomid, particularly zuclomiphene, can interfere with that final conversion. Desmosterol accumulates and rises. This isn’t fringe theory—it’s printed on the FDA label, which notes prolonged clomiphene therapy can elevate serum desmosterol.

But does elevated desmosterol translate into cardiovascular harm?

That connection has never been demonstrated in men. File this under “biochemical curiosity” rather than proven danger—worth knowing, not panicking over.

Response variability may trace to hepatic metabolism differences. CYP2D6 enzyme variations can dramatically alter how individuals metabolize clomiphene and experience estrogenic load.

Two men on identical doses but different liver genetics can have wildly divergent experiences.

The Two-Face Problem: When Labs Look Great But Symptoms Don’t Budge

Can enclomiphene raise testosterone? Absolutely, unequivocally yes.

A 2025 meta-analysis of randomized trials encompassing 10 studies and 819 men found selective estrogen receptor modulator (SERM) therapy raised total testosterone versus placebo by a mean difference of approximately 274 ng/dL, with significant LH and FSH increases.

Older comparisons showed median testosterone climbing from 247 ng/dL to around 504 ng/dL on clomiphene.

The number reliably moves upward.

But raising lab values and improving quality of life are entirely separate outcomes—the identical problem that sank Androxal’s FDA application.

Symptom data represents the soft underbelly of the entire enclomiphene story.

In blinded comparisons, traditional testosterone therapy consistently outperforms clomiphene for patient-reported outcomes—especially libido. One head-to-head trial found both TRT and Clomid elevated testosterone, but TRT delivered superior symptom relief with specific libido concerns in the clomiphene cohort.

FDA reviewers examining enclomiphene for compounding stated the conclusion plainly: trials raised testosterone, LH, and FSH, but failed to adequately demonstrate clinically meaningful improvements in symptoms, signs, or quality of life.

The labs improved more convincingly than the lives.

The IGF-1 Complication

Growing concern centers on SERMs potentially suppressing IGF-1 (insulin-like growth factor 1)—growth hormone’s downstream muscle and skeletal messenger.

A 2025 UCLA study examining 20 hypogonadal men on clomiphene found 75% experienced IGF-1 declines. In several cases, drops exceeded two standard deviations below normal—potentially clinically significant.

The mechanism aligns: increased estrogen signaling activates Sox3 protein, which impairs hepatic growth hormone signaling and pulls IGF-1 downward. Older SERM research supports this—tamoxifen reduced IGF-1 approximately 25% in healthy men.

Two critical caveats deserve mention. First, the UCLA cohort was atypical—most subjects had pituitary lesion histories. Second, lower IGF-1 on paper doesn’t equal proven harm to body composition, glucose metabolism, or bone density.

But if testosterone optimization aims to build muscle and enhance recovery, unmonitored IGF-1 quietly sliding represents an ironic plot twist.

The Maddening Variability Nobody Wants to Discuss

Clinical practice reveals what meta-analyses can’t fully capture: response is wildly unpredictable.

Some men experience phenomenal transformations—energy restored, libido returned, labs gorgeous, patients thrilled.

Others with identical starting labs and dosing report feeling absolutely nothing despite testosterone climbing beautifully.

Same drug, two faces. The coin lands differently, and prediction before trial remains impossible.

Why such variability?

• Low testosterone symptoms overlap extensively with sleep deprivation, depression, obesity, stress, and alcohol consumption
• Raising one hormone doesn’t address multifactorial issues
• Total testosterone doesn’t always reflect free testosterone or tissue-level receptor activity
• Blocking peripheral estrogen receptors might inhibit estrogen signaling men actually require for libido, erectile function, and mood

Estradiol isn’t exclusively a women’s hormone. Studies demonstrate isolated estrogen deficiency in men drives fat accumulation and destroys sexual function.

Enclomiphene could theoretically raise testosterone while simultaneously disrupting beneficial estrogen signaling—leaving men feeling no better despite impressive lab numbers.

Additionally, virtually no long-term safety data exists for men taking enclomiphene for years. Trials measured outcomes in months, not decades.

The Verdict: Who Should Flip This Coin?

Dr. Alex’s position, informed by prescribing thousands of scripts primarily for male fertility, breaks down clearly:

Enclomiphene is a fantastic fertility-boosting medication for men with low sperm counts absent other identifiable causes like varicoceles. Full stop.

For younger men with low testosterone who want to preserve fertility while attempting testosterone optimization, enclomiphene remains a tool worth trying.

As a pure low-testosterone treatment in men without immediate fertility concerns? More Two-Face than Harvey Dent—highly variable, and anyone claiming otherwise is selling something.

The genuinely good news: enclomiphene is oral, widely considered safe, not controlled (avoiding DEA refill theatrics), and won’t destroy fertility.

Two Non-Negotiable Rules

Rule One: Listen to your body, not just lab printouts. Numbers ascending isn’t the sole objective—feeling and functioning better represents the actual goal. Don’t allow anyone to gaslight you into ignoring subjective experience just because total testosterone looks pretty on paper.

Rule Two: Ensure your provider is comfortable advancing treatment if the coin flip fails. If enclomiphene doesn’t deliver, you need a physician willing to escalate to actual testosterone therapy—ideally with human chorionic gonadotropin (HCG) if fertility preservation matters—not someone who keeps prescribing the same ineffective drug hoping for different results.

A drug that works for some men isn’t a moral failing when it doesn’t work for you. It simply means you needed the alternative treatment.

And there’s literally zero reason any man should receive old-school clomiphene citrate in 2025. Twice the estrogenic risk with no additional benefit.

The Bottom Line on Medicine’s Most Two-Faced Drug

Enclomiphene sits at a fascinating intersection of legitimate medicine and aggressive marketing, regulatory failure and clinical necessity, proven mechanism and unpredictable outcomes.

For fertility preservation and support, it’s an industry staple with solid justification. For general testosterone optimization, it’s a reasonable first swing—but only with realistic expectations and a provider willing to pivot when needed.

The most tragic drugs are sometimes those with two faces but only one face on the label.

Proceed accordingly.