What’s the difference between enclomiphene and TRT?
Enclomiphene vs TRT comes down to where the testosterone comes from. TRT gives you testosterone from outside, so your body makes less of its own and sperm production falls. Enclomiphene is a pill that nudges your brain to tell your testes to make more of their own testosterone, and in trials it usually spared sperm.
There’s a big catch. Enclomiphene isn’t FDA-approved, and it only works if your testes and pituitary, the gland at the base of the brain, still work. TRT is approved and works whatever the cause of low testosterone.
This guide explains how each works, what the studies show for fertility and natural production, and where the regulators stand. It isn’t a recommendation for either, and it doesn’t suggest trying enclomiphene.
Because the drug isn’t approved, any decision about it belongs with your prescriber. For the bigger picture, see our starting TRT guide.
| TRT | Enclomiphene | |
|---|---|---|
| What it is | Testosterone, by injection, gel or other forms | A pill related to clomiphene |
| How it raises testosterone | Replaces it from outside | Pushes your own testes to make more |
| LH and FSH (brain signals) | Go down | Go up |
| Sperm production | Usually falls, sometimes to zero | Usually kept, in trials |
| Works if the testes have failed | Yes | No |
| FDA status | Approved | Not approved |
What is enclomiphene?
Enclomiphene is one of two forms that make up clomiphene, an older drug. The other form is zuclomiphene.
Zuclomiphene stays in the body much longer, and could still be found more than a month after a single dose. Some data suggest it acts more like estrogen.
In men taking clomiphene long term, the longer-lasting zuclomiphene dominated their blood, about 20 times more than enclomiphene. That’s one reason researchers developed enclomiphene on its own.
Both belong to a group of drugs called SERMs. They block estrogen’s effect in some parts of the body, including the pituitary.
How does TRT affect your own testosterone and sperm?
TRT turns down your own production. The drug label explains that testosterone from outside makes the pituitary release less LH, the signal that tells the testes to make testosterone. At higher exposure it also lowers FSH, which drives sperm production.
The effect on sperm can be large. In a World Health Organization study of 271 healthy men on weekly testosterone injections, 65% had no sperm in their semen within 6 months.
It usually comes back after stopping, but slowly. In studies of healthy men, sperm counts recovered in 67% within 6 months, 90% within 12 and all within 24. Our guide to TRT and fertility covers this in detail.
How does enclomiphene work differently?
It works through the same signals, in the opposite direction. Estrogen normally acts as a brake on the pituitary. Enclomiphene blocks that brake, so the pituitary releases more LH and FSH, and the testes make more testosterone and sperm.
That only helps if the system can respond. Reviews note that clomiphene-type drugs need a working pituitary and testes. They don’t work in primary hypogonadism, where the testes themselves have failed, because LH and FSH are already high there.
That’s why the cause of your low testosterone matters. Our guide to how low T is diagnosed explains how LH and FSH tests tell the types apart.
Is enclomiphene FDA-approved?
No. Its only US application, from a company called Repros, got a Complete Response in December 2015. That means the FDA couldn’t approve it as it was.
The FDA said the trial design was no longer adequate to show clinical benefit. Europe’s medicines regulator refused it in 2018.
In 2022, the FDA reviewed whether pharmacies should be allowed to compound enclomiphene. Its review said the trials showed higher testosterone, LH and FSH, but not clear improvement in symptoms. It also listed safety concerns: heart and clot events, and rises in estradiol, PSA and hematocrit.
The FDA’s advisory committee then voted 8 to 4 against adding enclomiphene to the list of substances pharmacies may compound. Even so, the FDA’s list, last updated in May 2026, still places it in a category under review, where the FDA doesn’t currently act against pharmacies that meet certain conditions.
Enclomiphene isn’t FDA-approved, and compounded versions aren’t checked by the FDA for safety, strength or quality.
That matters for safety. The FDA says compounded drugs aren’t FDA-approved, and that it doesn’t verify their safety, effectiveness or quality before they’re sold.
How is enclomiphene sold in the US?
Mostly through compounding pharmacies. These are pharmacies that mix their own versions of drugs. Because enclomiphene is still under FDA review for compounding, some pharmacies make it.
That’s not the same as an approved drug. No one at the FDA checks each batch for strength or purity. The product you get may not match what was tested in trials.
If a clinic offers enclomiphene, ask where it comes from. Ask whether it’s compounded, and who checks its quality.
What happens when you stop enclomiphene?
The effect fades fairly fast. In one small trial, testosterone was back to where it started a month after stopping. In another, the rise in LH and testosterone lasted at least a week after the last pill.
That’s different from TRT. After TRT, your own production can take months to restart. With enclomiphene, your own system was working the whole time.
What about clomiphene?
Clomiphene is FDA-approved, but only for ovulation problems in women. Prescribing it to men is off-label, meaning outside its approved use. Its label says there are no adequate studies showing it works for male infertility, and that testicular tumors and breast growth have been reported in men taking it.
It has a longer track record in men. In one retrospective review of 400 men, 88% of those on clomiphene for more than 3 years reached normal testosterone.
Of those long-term users, 77% reported better symptoms and 8% reported side effects. The most common were mood changes, blurred vision and breast tenderness, each in a handful of men.
A review of 19 studies with 1,642 men found that testosterone, LH, FSH and estradiol all rose on clomiphene. Side effects were reported in fewer than 10% of men, but only 4 of those studies were randomized. Reviews also mention headache, dizziness, breast growth and worsening of mental health conditions.
Does enclomiphene work as well as TRT?
For hormone levels, often yes, though that isn’t the same as the same benefit. In small trials, enclomiphene raised testosterone to levels similar to a testosterone gel, while LH and FSH went up instead of down. A review of randomized trials found clomiphene-type drugs raised testosterone, LH and FSH compared with placebo, with no clear difference from gel.
A review of clomiphene against TRT found similar testosterone levels compared with gels. But in one study, injections reached higher levels, and libido scores were lower on clomiphene. The authors called the findings preliminary.
The bigger question is symptoms. The FDA’s 2022 review said trials didn’t show clinically meaningful improvement in symptoms or signs of low testosterone. Not everyone responds either: in one study of clomiphene, 62% of men met the definition of a responder.
What do they do to sperm and fertility?
In trials, enclomiphene-type drugs kept sperm production while TRT lowered it. In two phase 3 trials in overweight men, enclomiphene kept sperm counts in the normal range over 16 weeks. On a testosterone gel, sperm production fell sharply.
In a clinic comparison, total motile sperm count rose on enclomiphene but not on clomiphene. A review of clomiphene in infertile men found sperm concentration rose by about 8 million per mL on average. In 10 of those studies, pregnancy rates averaged 17%, ranging from 0 to 40%.
Guidelines agree on one thing: testosterone on its own should not be prescribed to a man who wants children now or later, according to the AUA and the American Society for Reproductive Medicine. The Endocrine Society also advises against starting TRT if you’re planning fertility soon. Which option fits you, if any, is a conversation for your prescriber or a fertility specialist.
What side effects have been reported?
Less is known about enclomiphene than about TRT, because it hasn’t been through full approval. In an open-label safety study of about 500 men, serious events included clots in the legs and lungs, an irregular heartbeat and a testicular tumor. Without a comparison group, the study can’t show whether enclomiphene caused them.
Europe’s review noted blurred vision, muscle spasm, headache and aggression as reasons men stopped. It also found heart and clot events slightly more often than in men on testosterone. In a clinic study, men had fewer side effects on enclomiphene than on clomiphene, including less mood change and a smaller rise in estradiol.
For clomiphene, the label warns about blurred vision and spots or flashes, which can occasionally last after stopping. It says anyone with visual symptoms should stop and have an eye exam. Get emergency help (call 911) for chest pain, sudden breathlessness or a painful, swollen leg, and call your prescriber right away about any vision changes.
What doesn’t the evidence show yet?
There are real gaps. Keep these in mind:
- Symptoms: trials mostly measured hormone levels, not how men felt.
- Long-term safety: most studies lasted weeks or months, not years.
- Big outcomes: no trial has looked at heart attacks, fractures or long-term health.
- Your own response: some men don’t respond, and it’s hard to predict who.
The FDA also said that a rise in sperm counts isn’t enough on its own to prove a benefit. So enclomiphene isn’t proven as a fertility treatment either.
Who shouldn’t use enclomiphene?
Men whose testes have failed won’t benefit, because the drug works by raising signals the testes can’t answer. The Endocrine Society also says the cause of low testosterone should be found before treatment is chosen. Reviews also advise against clomiphene-type drugs in men with a history of blood clots.
A UK specialist society said in 2026 that enclomiphene looks promising but that evidence comes from small, short studies with limited safety data. It doesn’t recommend routine use outside specialist settings.
Before any decision, your prescriber will want to know why your testosterone is low, and LH and FSH tests help answer that. Keep a record of your symptoms and results. Our draw-date planner helps you time your blood tests.
What should you ask your prescriber about enclomiphene vs TRT?
- What’s causing my low testosterone, and would my testes respond to enclomiphene or clomiphene?
- If I might want children, which option protects my fertility best?
- Is the product you’d prescribe FDA-approved, off-label or compounded?
- What side effects should I watch for, and how will we check my blood?
- If I’m on TRT now, what would switching involve and how long would recovery take?
- How will we know if it’s working, and what do we do if it isn’t?
Bring your recent lab results and a short list of your symptoms. Write down the answers, so you can compare them with your results over the next few months.
If you change treatments, note the date and keep testing on a steady schedule. That makes it easier to see what changed and why.