Why do men lose erections after they ejaculate?

From a reproductive standpoint, the purpose of an erection⁠ (erection: When a body part, such as the penis or parts of the vulva, becomes filled with blood and enlarges and/or becomes more firm.) is to allow for insertion of the penis⁠ (penis: One of the two external reproductive organs of people often assigned male at birth.) into the vaginal canal and ejaculation⁠ (ejaculation: In a sexual context, a discharge of genital fluid, usually (but not always) as a result of sexual stimulation and/or orgasm.) . Once the erection has served that purpose, there is no reason for it to continue. Also, typically after ejaculation or orgasm⁠ (orgasm: An event typically in response to physical or intellectual sexual stimulation, controlled by the involuntary nervous system. ) , sexual⁠ (sexual: About or relating in some way to sex or sexuality.) arousal⁠ (arousal: A state of sexual excitement and interest that sends messages to the brain which create physical changes and sensations, such as increased blood pressure, erection, lubrication, loosening of the vaginal or anal muscles, and increased physical sensitivity.) wans. As that arousal goes down, so does an erection. The same sort of thing happens in people with vaginas as well. During sexual activity, the body and genitals⁠ (genitals: Body parts that are generally, culturally, scientifically or personally considered to be external sexual or reproductive organs.) are aroused. This includes extra blood rushing to the genital region, swelling in that area, relaxation and lubrication of the vaginal canal, etc. Once sexual activity ends, those signs of arousal will subside. If desired, after a “refractory period⁠ (period: The fluid – or flow – which contains blood, from the shedding of the uterine lining usually at the end of each menstrual cycle. Sometimes periods may be less fluid and more globby; this is the state that is often mistaken for blood clotting.) ”, arousal can generally be achieved again. (You also may want to keep in mind that there are many types of sexual activity that do not require an erection. So just because an erection ends, that does not mean sexual activity is automatically over if you don’t want it to be as well.)

It is also important to remember that it is also necessary for arousal to go down after sexual activity is over. During an erection, the blood vessels of the penis constrict to allow the erection to occur. If that constriction continues for too long, the cells can actually be damaged. This condition is called priapism (find out more about the condition and it’s treatment at this page on WebMDexternal link, opens in a new tab) and can cause permanent damage and be very painful. This condition is not something that happens on a regular basis (it’s most often associated with things like sickle-cell disease, leukemia, malaria or medications used to treat erectile dysfunction) because the body is designed to know when it’s time to relax, but it does happen for some people.

You might want to check out the following links:

• Innies & Outies: The Penis, Testes, and More
• Sexual Health 101: His
• Sexual Response & Orgasm: A Users Guide