If a man takes female birth control pills regularly, the estrogen and progestin will suppress his body’s natural testosterone production, leading to a range of physical, sexual, and emotional changes. The effects start subtly but become more pronounced over weeks and months, and some are not fully reversible after stopping.
Most combined oral contraceptives contain around 0.020 to 0.035 mg of ethinyl estradiol plus a progestin. That dose is lower than what’s typically prescribed in feminizing hormone therapy, but it’s enough to interfere with the hormonal feedback loop that controls testosterone in men. Some transgender women who self-prescribe hormones use these exact pills as a starting point.
How Birth Control Suppresses Testosterone
Testosterone production in men depends on signals from the brain. The hypothalamus and pituitary gland release hormones (LH and FSH) that tell the testes to produce testosterone and sperm. Estrogen is a key part of the feedback system that regulates those signals. When a man introduces external estrogen by taking birth control pills, his brain detects the elevated estrogen and dials back those signals. The testes then produce less testosterone.
This mechanism is well established. Synthetic estrogen was used as a prostate cancer treatment in the 1960s and 1970s specifically because it could suppress androgen production through this feedback loop. The estrogen in birth control pills works the same way, just at a lower dose. Over time, consistently suppressed LH and FSH lead to progressively lower testosterone levels.
Effects on Fertility and Sexual Function
Sperm production is one of the first things affected. When the brain stops sending signals to the testes, spermatogenesis slows dramatically. Hormonal contraceptive approaches tested in men have achieved sperm concentrations below 1 million per milliliter in roughly 95% of participants. For context, a normal sperm count is 15 million or more per milliliter. Birth control pills would push a man’s count far below the threshold needed for fertility, though the timeline depends on how much testosterone suppression actually occurs at those doses.
Sexual function also takes a hit. Lower testosterone typically means reduced libido, and some men experience difficulty with erections and ejaculation. In trials of experimental male hormonal contraceptives, about 10% of participants reported decreased erectile or ejaculatory function within just 28 days of daily dosing.
The longer a man takes these hormones, the greater the risk of lasting fertility problems. Long-term hormonal suppression can impair the testes’ ability to resume normal sperm production even after stopping the pills. Short-term use is more likely to be reversible, but there’s no clear cutoff for when the damage becomes permanent.
Breast Growth and Body Changes
Estrogen is the primary growth hormone of breast tissue. In men, excess estrogen triggers a condition called gynecomastia: the ducts in the breast begin to lengthen and branch, surrounding connective tissue proliferates, and blood flow to the area increases. Oral contraceptives are specifically classified as a type of medication that acts like estrogen and can cause gynecomastia.
In the early stages, breast tissue feels tender or swollen, often starting as a small, firm lump behind the nipple. Over months of continued use, actual breast development occurs. This is distinct from the “pseudogynecomastia” seen in overweight men, which is just fat deposition. Estrogen-driven gynecomastia involves real glandular tissue growth, and once that tissue has developed, it does not fully go away on its own. Surgical removal is typically the only way to reverse established breast growth.
Fat redistribution is another gradual change. Estrogen encourages fat storage in the hips, thighs, and buttocks rather than the abdomen. Skin may become softer, and body hair growth can slow as testosterone declines. These changes develop over months and are generally reversible once hormone levels normalize, unlike breast tissue.
Bone Density: A Complicated Picture
Estrogen plays a critical role in maintaining bone density in both men and women. Men who lack the ability to produce or respond to estrogen develop severe osteoporosis, and estrogen replacement markedly increases their bone mineral density. So in one sense, the estrogen from birth control pills could support bone health.
The problem is that suppressed testosterone creates its own risks for bones. The net effect depends on the balance between the two. In prostate cancer patients whose testosterone is suppressed by drugs that also lower estrogen, bone loss accelerates five to ten times faster than normal. But when estrogen is maintained while testosterone drops, bones are largely protected. Studies comparing estrogen-based treatments to testosterone-suppressing drugs found that estrogen users gained bone density (about 6.7% more in the spine after one year) while the other group lost it.
For a man taking birth control pills, the estrogen component would likely protect against the bone loss that low testosterone would otherwise cause. But this shouldn’t be mistaken for a health benefit, since the entire hormonal disruption is unnecessary and carries other serious risks.
Blood Clot Risk
The most dangerous short-term risk of a man taking birth control pills is venous thromboembolism: blood clots in the deep veins, which can travel to the lungs and become life-threatening. Oral estrogen increases clotting risk regardless of the user’s sex.
Among premenopausal women, oral contraceptives raise the incidence of blood clots from a baseline of 1 to 5 per 10,000 person-years to 3 to 9 per 10,000 person-years. In transgender women taking oral estrogen for feminization (often at higher doses), one retrospective study found that 5.1% experienced a blood clot over an average follow-up of 7.4 years, with nearly half of those events occurring within the first 12 months. High-dose oral ethinyl estradiol carries a particularly elevated risk.
Several factors compound this danger: higher body weight, older age, smoking, genetic clotting disorders like Factor V Leiden, and the oral route of administration itself. Transdermal estrogen (patches or gels) carries a much lower clotting risk than pills, because oral estrogen passes through the liver and increases the production of clotting factors. A man taking birth control pills gets the worst combination: oral estrogen with no medical monitoring.
Mood and Emotional Changes
Hormonal shifts affect mood, but the picture is less dramatic than many people expect. The interplay between falling testosterone and rising estrogen can cause irritability, low energy, and depressive symptoms, largely driven by testosterone loss. Some men report feeling more emotionally reactive or experiencing mood swings similar to what some women describe on hormonal contraceptives.
Research on estrogen’s direct effect on mood in people transitioning from male to female hormonal profiles has not shown consistent, large-scale emotional changes attributable to estrogen alone. The mood effects are real but variable, and they overlap heavily with the psychological impact of low testosterone: fatigue, reduced motivation, and a general sense of feeling “off.”
What Reverses and What Doesn’t
If a man stops taking birth control pills after a short period (a few weeks to a couple of months), most effects reverse as testosterone production recovers. Libido returns, mood stabilizes, and body fat gradually redistributes. Sperm production typically resumes, though it can take several months to reach normal levels.
After prolonged use, the picture changes. Breast tissue that has fully developed with glandular growth does not shrink back to a flat chest. It requires surgery. Fertility may not fully recover, especially after years of hormonal suppression. The testes may not regain their prior capacity, similar to what’s observed in other forms of long-term hormonal suppression where reproductive organs don’t fully bounce back even after treatment ends.
Fat redistribution, skin changes, and reduced body hair are generally reversible once testosterone levels normalize. The cardiovascular risks (blood clots, in particular) resolve relatively quickly after stopping, since clotting factor levels return to baseline within weeks. But a clot that has already formed is a medical emergency regardless of whether you’ve stopped the pills.