Study analysis · Canadian Urological Association journal = Journal de l'Association des urologues du Canada · 2026
This pill doubled men's testosterone—but made 7.5% of them sterile overnight.
A common fertility pill boosted sperm and hormones for most men, but some who could already have kids lost all sperm, and no one could predict who it would help or hurt.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study watched what happened to 60 guys after they took a pill for infertility, but didn't compare them to guys who didn't take the pill. So we can say the guys' sperm counts went up after taking it, but we don't know if the pill caused it—or if they just got better on their own.
What’s the bottom line?
Some men with unexplained infertility take a pill called clomiphene to help their bodies make more sperm and hormones. This study looked at 60 men who took it.
How strong is this study?
This study tried its best with what it had, but it's like trying to figure out if a new snack makes you stronger by only watching kids who chose to eat it—there's no fair test. Because there's no control group and no random assignment, we can't fully trust that the pill was the reason for the changes.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
19 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=60)+5.2/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 554 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
This design cannot establish causation — the findings describe an association, not a cause. This is a retrospective cohort study without randomization, control group, or blinding. Changes in sperm count and hormones occurred after clomiphene use, but other factors like natural variation, lifestyle changes, or unmeasured confounders could explain the results. Without a control group or random assignment, we cannot rule out that the improvements happened by chance or due to other reasons.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding disclosures were reported in the study text. All authors are affiliated with academic or clinical institutions without industry ties.
The study was conducted at academic institutions with no industry affiliations reported. No funding source is disclosed, and there is no indication of industry involvement in study design, analysis, or publication. The absence of a COI or funding statement limits full transparency but does not indicate bias based on available information.
Key takeaways
- 01
On average, sperm count went up by 13.1 million.
- 02
But 4 out of 7 men who had no sperm before got some after; 4 out of 53 men who had sperm lost it.
- 03
Hormones like testosterone doubled.
- 04
The average sperm increase might help some couples conceive naturally or avoid IVF, but for others, the pill made things worse — so it doesn't work the same for everyone.
Surprising findings
- 7.5% of men who had sperm before treatment became azoospermic after taking clomiphene.Clomiphene is marketed as a safe, natural way to boost fertility—no one expects it to cause complete sperm loss in otherwise fertile men. This contradicts the assumption that it only helps or does nothing.
- Azoospermia prevalence didn’t change overall—57% of azoospermic men gained sperm, but 7.5% of fertile men lost it.You’d expect the pill to reduce azoospermia rates—but it just shuffled men between categories with no net benefit. It’s a zero-sum game for the group.
- Higher baseline estradiol trended toward worse sperm response—even though estradiol increased overall.Estradiol is a byproduct of testosterone conversion and is often seen as harmless. But here, higher levels before treatment may signal a biological vulnerability to clomiphene’s side effects.
Practical takeaways
If considering clomiphene for unexplained infertility, get a baseline semen analysis and consider freezing sperm before starting.
This study was small, retrospective, and didn’t measure pregnancy outcomes—so we don’t know if improved sperm count actually leads to more babies.
medium confidenceAsk your doctor for a semen check at 6 months—if sperm count hasn’t improved or dropped, stop the drug.
The study didn’t define a clear 'response window,' but 6–9 months is suggested as a reasonable cutoff before continuing.
medium confidenceDon’t rely on testosterone or FSH levels to predict if clomiphene will work for you.
Hormone levels changed in everyone—but those changes didn’t correlate with sperm outcomes. Blood tests are misleading here.
high confidenceWhy this study matters
Sperm Count Jumped—But So Did the Risk
In 60 men with unexplained infertility, clomiphene citrate increased average total motile sperm count by 13.1 million (from 5.7M to 18.8M), with testosterone nearly doubling. But 7.5% of men who had sperm before treatment became azoospermic—meaning they produced zero sperm—while 57% of previously azoospermic men gained detectable sperm.
This isn't just 'it works for some'—it's a biological gamble: the same pill that gives hope to men with no sperm can erase fertility in men who already had it, making it a high-stakes, unpredictable treatment.
No One Can Predict Who It Will Work For
Researchers tested age, BMI, baseline hormone levels (testosterone, FSH, LH, estradiol, 17-OHP), and treatment duration—but none predicted whether a man’s sperm count would improve, stay the same, or crash. The study found zero statistically significant predictors (all p > 0.05).
Doctors routinely prescribe this based on hormone tests—but this study proves those tests are useless for predicting success. It’s like prescribing a cancer drug without knowing who will respond.
It Doesn’t Matter If You’ve Had a Baby Before
Men with primary infertility (never conceived) and secondary infertility (had a child before) showed identical improvements in sperm count and hormone levels. The pill worked just as well for both groups.
Most assume past fertility predicts future response—but this study says no. Even men who fathered kids before can benefit—or be harmed—just like first-time dads.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Some men with unexplained infertility take a pill called clomiphene to help their bodies make more sperm and hormones. This study looked at 60 men who took it.
Research results
On average, sperm count went up by 13.1 million. But 4 out of 7 men who had no sperm before got some after; 4 out of 53 men who had sperm lost it. Hormones like testosterone doubled.
What this means - more context
The average sperm increase might help some couples conceive naturally or avoid IVF, but for others, the pill made things worse — so it doesn't work the same for everyone.
This study evaluates whether clomiphene citrate improves total motile sperm count and reproductive hormones in men with idiopathic infertility.
In 60 men with idiopathic infertility, clomiphene citrate was associated with a mean increase of 13.1 million in total motile sperm count and significant rises in testosterone, FSH, LH, estradiol, and 17-OHP. Response was highly variable: 57% of azoospermic men gained detectable sperm, but 7.5% of those with sperm became azoospermic, with no net change in azoospermia prevalence. No baseline factors predicted response.
Methods Used
Single-center retrospective cohort of 60 men treated with oral clomiphene citrate (25–50 mg every other day) for an average of 13 months. Primary outcome: change in total motile sperm count. Hormonal changes assessed via paired t-tests; predictors analyzed with multivariable linear regression.
Main Finding
Clomiphene citrate was associated with a mean increase of 13.1 million in total motile sperm count (p=0.005) and significant increases in testosterone (+9.9 nmol/L), FSH (+4.9 IU/L), LH (+4.8 IU/L), estradiol (+53.9 pmol/L), and 17-OHP (+1.8 nmol/L), but individual responses varied widely and were not predictable by baseline clinical or hormonal parameters.
Confidence Level
Low to moderate; retrospective design, no control group, small sample, incomplete hormone data, and uncontrolled dosing limit causal inference.
Study Flags
Red Flags
- •No control group
- •Retrospective design with potential selection bias
- •High variability in response with no predictive biomarkers
Surprising Findings
7.5% of men who had sperm before treatment became azoospermic after taking clomiphene.
Clomiphene is marketed as a safe, natural way to boost fertility—no one expects it to cause complete sperm loss in otherwise fertile men. This contradicts the assumption that it only helps or does nothing.
Practical Takeaways
If considering clomiphene for unexplained infertility, get a baseline semen analysis and consider freezing sperm before starting.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 554 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Human Cohort Study
Subject
Moderate probability
on the GRADE evidence scale
This study watched what happened to 60 guys after they took a pill for infertility, but didn't compare them to guys who didn't take the pill. So we can say the guys' sperm counts went up after taking it, but we don't know if the pill caused it—or if they just got better on their own.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Used paired pre-post measurements to assess change within individuals
- Included multiple relevant outcomes (TMSC and 5 hormones)
- Used appropriate statistical tests (paired t-tests, regression)
Weaknesses
- No control group to compare against natural variation or placebo
- Retrospective design increases risk of recall and selection bias
- Blinding was unknown and likely absent
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Some men with unexplained infertility take a pill called clomiphene to help their bodies make more sperm and hormones. This study looked at 60 men who took it.
Research results
On average, sperm count went up by 13.1 million. But 4 out of 7 men who had no sperm before got some after; 4 out of 53 men who had sperm lost it. Hormones like testosterone doubled.
What this means - more context
The average sperm increase might help some couples conceive naturally or avoid IVF, but for others, the pill made things worse — so it doesn't work the same for everyone.
This study evaluates whether clomiphene citrate improves total motile sperm count and reproductive hormones in men with idiopathic infertility.
In 60 men with idiopathic infertility, clomiphene citrate was associated with a mean increase of 13.1 million in total motile sperm count and significant rises in testosterone, FSH, LH, estradiol, and 17-OHP. Response was highly variable: 57% of azoospermic men gained detectable sperm, but 7.5% of those with sperm became azoospermic, with no net change in azoospermia prevalence. No baseline factors predicted response.
Methods Used
Single-center retrospective cohort of 60 men treated with oral clomiphene citrate (25–50 mg every other day) for an average of 13 months. Primary outcome: change in total motile sperm count. Hormonal changes assessed via paired t-tests; predictors analyzed with multivariable linear regression.
Main Finding
Clomiphene citrate was associated with a mean increase of 13.1 million in total motile sperm count (p=0.005) and significant increases in testosterone (+9.9 nmol/L), FSH (+4.9 IU/L), LH (+4.8 IU/L), estradiol (+53.9 pmol/L), and 17-OHP (+1.8 nmol/L), but individual responses varied widely and were not predictable by baseline clinical or hormonal parameters.
Confidence Level
Low to moderate; retrospective design, no control group, small sample, incomplete hormone data, and uncontrolled dosing limit causal inference.
Study Flags
Red Flags
- •No control group
- •Retrospective design with potential selection bias
- •High variability in response with no predictive biomarkers
Surprising Findings
7.5% of men who had sperm before treatment became azoospermic after taking clomiphene.
Clomiphene is marketed as a safe, natural way to boost fertility—no one expects it to cause complete sperm loss in otherwise fertile men. This contradicts the assumption that it only helps or does nothing.
Practical Takeaways
If considering clomiphene for unexplained infertility, get a baseline semen analysis and consider freezing sperm before starting.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 554 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Human Cohort Study
Subject
Moderate probability
on the GRADE evidence scale
This study watched what happened to 60 guys after they took a pill for infertility, but didn't compare them to guys who didn't take the pill. So we can say the guys' sperm counts went up after taking it, but we don't know if the pill caused it—or if they just got better on their own.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Used paired pre-post measurements to assess change within individuals
- Included multiple relevant outcomes (TMSC and 5 hormones)
- Used appropriate statistical tests (paired t-tests, regression)
Weaknesses
- No control group to compare against natural variation or placebo
- Retrospective design increases risk of recall and selection bias
- Blinding was unknown and likely absent
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
This study tried its best with what it had, but it's like trying to figure out if a new snack makes you stronger by only watching kids who chose to eat it—there's no fair test. Because there's no control group and no random assignment, we can't fully trust that the pill was the reason for the changes.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
19 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=60)+5.2/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 554 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
This design cannot establish causation — the findings describe an association, not a cause. This is a retrospective cohort study without randomization, control group, or blinding. Changes in sperm count and hormones occurred after clomiphene use, but other factors like natural variation, lifestyle changes, or unmeasured confounders could explain the results. Without a control group or random assignment, we cannot rule out that the improvements happened by chance or due to other reasons.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding disclosures were reported in the study text. All authors are affiliated with academic or clinical institutions without industry ties.
The study was conducted at academic institutions with no industry affiliations reported. No funding source is disclosed, and there is no indication of industry involvement in study design, analysis, or publication. The absence of a COI or funding statement limits full transparency but does not indicate bias based on available information.