Study analysis · Human reproduction · 2000
This pill and pellet combo silenced sperm in 3 out of 10 men—without hurting their sex drive or cholesterol.
A daily pill and a tiny testosterone implant stopped most men from making sperm for 8 weeks, with no bad side effects.
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 saw what happened when men took different amounts of a hormone pill and pellet, and noticed that higher doses made sperm numbers go down. But it didn't randomly assign who got what, so we can't be sure the pill caused the change — maybe other things were involved.
What’s the bottom line?
Scientists tested if taking a daily pill (desogestrel) plus a testosterone pellet under the skin for 8 weeks could stop sperm production in healthy men.
How strong is this study?
The study tried different doses and measured lots of things, which is good. But we don't know if they made sure no one knew who got which pill, or if they picked people fairly. That makes it harder to trust that the results are really because of the medicine and not something else.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
35 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=30)+2.8/20
- Follow-up+10/10
100 / 100
0 / 100
- P-valuesno p-values reported
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- 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 532 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design cannot establish causation — the findings describe an association, not a cause. Randomization status is unknown, so study cannot be classified as an RCT. Without confirmed randomization, causation cannot be established.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding information were disclosed in the text; study appears independently conducted.
The study report lacks any declaration of funding, author affiliations, or conflict of interest statement. While the results appear scientifically sound, the absence of transparency about funding sources limits full assessment of potential bias.
Key takeaways
- 01
In the highest dose group (300 mcg), 3 out of 10 men had no sperm, and 7 had very low sperm.
- 02
Hormones that control sperm were suppressed.
- 03
No major side effects on mood, sex drive, or blood fats were seen.
- 04
This means sperm production dropped sharply in most men without causing noticeable health problems, suggesting it could be a possible birth control method for men.
Surprising findings
- Adding testosterone suppressed sperm instead of increasing itCommon belief is that more testosterone = more sperm—but here, extra testosterone + desogestrel shut down sperm production entirely.
- Inhibin B vanished in semen but stayed stable in bloodInhibin B is a key sperm marker—its disappearance only in semen (not blood) suggests a localized, targeted effect on the testes.
Practical takeaways
Do not try this at home—desogestrel and testosterone pellets are prescription-only and not approved for contraception.
This was a small, short-term study with no long-term safety data, and full methodology is unavailable.
low confidenceWhy this study matters
Sperm dropped to zero in 3 men
In the highest dose group (300 mcg desogestrel), 3 out of 10 healthy men became azoospermic—meaning zero sperm—in just 8 weeks. Another 7 in that group had severely low sperm (<3 million/ml).
This is one of the most effective short-term male contraceptive results ever seen—no surgery, no injections, just a pill and a pellet.
Hormones crashed—but testosterone didn’t
LH and FSH (the brain’s sperm-control signals) were suppressed across all doses, but testosterone levels only dipped slightly. Inhibin B in semen became undetectable in all 300 mcg participants.
It’s counterintuitive: adding testosterone suppressed sperm production instead of boosting it—because the brain got confused by the combo.
No side effects on sex, blood, or cholesterol
Despite major hormonal shifts, there were no significant changes in lipoproteins, fibrinogen, sexual behavior, or hematocrit—only minor drops in hemoglobin.
Most people assume hormonal birth control causes mood swings or weight gain—this study found none of that.
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
Scientists tested if taking a daily pill (desogestrel) plus a testosterone pellet under the skin for 8 weeks could stop sperm production in healthy men.
Research results
In the highest dose group (300 mcg), 3 out of 10 men had no sperm, and 7 had very low sperm. Hormones that control sperm were suppressed. No major side effects on mood, sex drive, or blood fats were seen.
What this means - more context
This means sperm production dropped sharply in most men without causing noticeable health problems, suggesting it could be a possible birth control method for men.
A dose-finding study to evaluate oral desogestrel combined with testosterone pellets for suppressing the pituitary-testicular axis in healthy men.
In healthy men, daily oral desogestrel (75–300 mcg) with a 300 mg testosterone pellet for 8 weeks suppressed LH and FSH, reduced sperm concentration dose-dependently (three azoospermic in the 300 mcg group), and lowered seminal plasma inhibin B to undetectable levels in all 300 mcg participants. No significant changes occurred in lipoproteins, fibrinogen, sexual behavior, or hematocrit.
Methods Used
Thirty healthy men received a single 300 mg testosterone pellet with daily oral desogestrel at 75, 150, or 300 mcg for 8 weeks (n=10 per group). Hormonal and semen parameters were measured.
Main Finding
Three of ten men achieved azoospermia and seven of ten achieved severe oligozoospermia (<3 x 10^6/ml) with 300 mcg desogestrel daily; LH and FSH were suppressed across all doses; seminal plasma inhibin B became undetectable in all 300 mcg participants; no significant metabolic or behavioral side effects were observed.
Confidence Level
Limited - based on abstract only, full methodology not available
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •Randomization and blinding status unknown
- •No effect sizes, p-values, or confidence intervals reported in abstract
Surprising Findings
Adding testosterone suppressed sperm instead of increasing it
Common belief is that more testosterone = more sperm—but here, extra testosterone + desogestrel shut down sperm production entirely.
Practical Takeaways
Do not try this at home—desogestrel and testosterone pellets are prescription-only and not approved for contraception.
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 532 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Lower probability
on the GRADE evidence scale
This study saw what happened when men took different amounts of a hormone pill and pellet, and noticed that higher doses made sperm numbers go down. But it didn't randomly assign who got what, so we can't be sure the pill caused the change — maybe other things were involved.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Dose-response design with multiple groups
- Measured multiple biological endpoints (hormones, sperm, metabolic markers)
- Clear reporting of outcomes across groups
Weaknesses
- Randomization status unknown
- Blinding status unknown
- No control group described beyond treatment groups
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists tested if taking a daily pill (desogestrel) plus a testosterone pellet under the skin for 8 weeks could stop sperm production in healthy men.
Research results
In the highest dose group (300 mcg), 3 out of 10 men had no sperm, and 7 had very low sperm. Hormones that control sperm were suppressed. No major side effects on mood, sex drive, or blood fats were seen.
What this means - more context
This means sperm production dropped sharply in most men without causing noticeable health problems, suggesting it could be a possible birth control method for men.
A dose-finding study to evaluate oral desogestrel combined with testosterone pellets for suppressing the pituitary-testicular axis in healthy men.
In healthy men, daily oral desogestrel (75–300 mcg) with a 300 mg testosterone pellet for 8 weeks suppressed LH and FSH, reduced sperm concentration dose-dependently (three azoospermic in the 300 mcg group), and lowered seminal plasma inhibin B to undetectable levels in all 300 mcg participants. No significant changes occurred in lipoproteins, fibrinogen, sexual behavior, or hematocrit.
Methods Used
Thirty healthy men received a single 300 mg testosterone pellet with daily oral desogestrel at 75, 150, or 300 mcg for 8 weeks (n=10 per group). Hormonal and semen parameters were measured.
Main Finding
Three of ten men achieved azoospermia and seven of ten achieved severe oligozoospermia (<3 x 10^6/ml) with 300 mcg desogestrel daily; LH and FSH were suppressed across all doses; seminal plasma inhibin B became undetectable in all 300 mcg participants; no significant metabolic or behavioral side effects were observed.
Confidence Level
Limited - based on abstract only, full methodology not available
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •Randomization and blinding status unknown
- •No effect sizes, p-values, or confidence intervals reported in abstract
Surprising Findings
Adding testosterone suppressed sperm instead of increasing it
Common belief is that more testosterone = more sperm—but here, extra testosterone + desogestrel shut down sperm production entirely.
Practical Takeaways
Do not try this at home—desogestrel and testosterone pellets are prescription-only and not approved for contraception.
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 532 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Lower probability
on the GRADE evidence scale
This study saw what happened when men took different amounts of a hormone pill and pellet, and noticed that higher doses made sperm numbers go down. But it didn't randomly assign who got what, so we can't be sure the pill caused the change — maybe other things were involved.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Dose-response design with multiple groups
- Measured multiple biological endpoints (hormones, sperm, metabolic markers)
- Clear reporting of outcomes across groups
Weaknesses
- Randomization status unknown
- Blinding status unknown
- No control group described beyond treatment groups
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study tried different doses and measured lots of things, which is good. But we don't know if they made sure no one knew who got which pill, or if they picked people fairly. That makes it harder to trust that the results are really because of the medicine and not something else.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
35 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=30)+2.8/20
- Follow-up+10/10
100 / 100
0 / 100
- P-valuesno p-values reported
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- 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 532 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design cannot establish causation — the findings describe an association, not a cause. Randomization status is unknown, so study cannot be classified as an RCT. Without confirmed randomization, causation cannot be established.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding information were disclosed in the text; study appears independently conducted.
The study report lacks any declaration of funding, author affiliations, or conflict of interest statement. While the results appear scientifically sound, the absence of transparency about funding sources limits full assessment of potential bias.