If a guy takes a single dose of Plan B, essentially nothing happens. The pill contains 1.5 mg of levonorgestrel, a synthetic form of progesterone designed to prevent ovulation in people with ovaries. In a male body, there’s no ovulation to suppress, and a one-time dose at that level won’t produce any noticeable physical effects.
Why a Single Dose Won’t Do Anything
Plan B works by delivering a short burst of synthetic progesterone that delays or blocks the release of an egg from the ovary. Men don’t ovulate, so the drug has no reproductive target to act on. The 1.5 mg dose is also quite small in the context of male hormone levels. Your body already produces hormones in quantities that dwarf what’s in one pill, so a single dose gets processed by the liver and cleared without causing symptoms.
You won’t feel nauseous, grow breasts, or experience any feminizing changes from taking one pill. There’s no medical emergency, no need to call poison control, and no lasting effect on your hormones or fertility.
What Repeated Use Would Actually Do
The story changes if a man were to take progestins like levonorgestrel regularly over weeks or months. In that scenario, the synthetic progesterone begins to interfere with the hormonal signals that drive sperm production and testosterone release.
Levonorgestrel binds to androgen receptors (the same receptors testosterone uses) and also affects the brain’s signaling to the testes. When taken daily, this suppresses two key hormones from the pituitary gland that tell the testes to produce sperm and testosterone. In a study where men took daily levonorgestrel for eight to nine months alongside testosterone, their natural testosterone production dropped significantly and sperm counts fell. After they stopped, sperm counts, testosterone, and hormone levels returned to normal over a recovery period of five to ten months.
Regular use of a progestogen-only pill would primarily reduce sperm count and lower sex drive. It would not cause breast growth or other feminizing effects on its own, because levonorgestrel doesn’t activate estrogen receptors. The combined pill, which contains both estrogen and a progestin, is a different story. Taking that regularly could cause mild feminizing changes like softer skin and slight breast tissue development, because it delivers estrogen directly.
It Won’t Work as Male Birth Control
A common follow-up question is whether Plan B could function as some kind of male contraceptive. It can’t. Emergency contraception prevents pregnancy by acting on the ovary and uterine environment. Taking it as a man does nothing to reduce your fertility in any practical sense. Even in research settings where daily progestins did suppress sperm counts, the effect took months to develop, required consistent dosing, and was paired with other hormones under medical supervision. A single Plan B pill doesn’t come close to affecting sperm production.
Researchers have explored progestins as one component of experimental male contraceptives, but those regimens look nothing like popping a Plan B. They involve carefully calibrated combinations of hormones given over long periods, and none are currently approved for use.
The Bottom Line on Safety
A man who swallows a Plan B pill, whether out of curiosity, by accident, or as a joke, has nothing to worry about. The hormone is processed and eliminated by the body without producing meaningful effects. There’s no danger, no side effects to watch for, and no reason to seek medical attention. It’s pharmacologically uneventful. The pill simply wasn’t designed to interact with male reproductive biology in any significant way at a single dose.