Barring the transmission of diseases that can be transmitted sexually and the spreading of blood-borne infections, it is generally safe to have sex during menstruation. Having sex during a period won’t harm the menstruating woman or her partner. This doesn’t mean that a woman who has sex during her period cannot become pregnant, however. It is possible that sperm that enter her body during menstruation may survive long enough to fertilize an egg that is released later. For these reasons, if sexually transmitted disease (STD) risk or pregnancy is a concern, a couple may be wise to use a condom at this time or abstain from sexual intercourse.

Generally, sex is safe during menstruation. None of the physical processes that occur during menstruation are dangerous for the menstruating woman or her sexual partner. In fact, many women find sex during menstruation helps to relieve some of the more unpleasant symptoms that often accompany menstruation. For example, a woman may find that it helps to relieve cramps and tension. Some women even assert that sex helps relieve menstruation-related headaches and irritability.

Many women also find that pleasurable feelings are increased when they have sex during menstruation. For example, some women are more aroused during menstruation, and others find it easier to have orgasms during this time. This may be due, at least in part, to the fact that menstrual periods are associated with increased feelings of fullness in a female's genital area.

Just how safe sex is during menstruation may depend on whether or not a couple uses protection or is certain that both parties are free of STDs. During menstruation, a woman’s cervix opens to allow menstrual blood to pass through, which means a woman may be even more susceptible to sexually transmitted infections than at other times in her cycle. A menstruating woman may also be more likely pass blood-borne infections on to her sexual partner during this time. Even yeast infections may be more likely to take hold during menstruation because of changes in the pH of the vagina. To keep sex safe during menstruation, people who are not certain they are in monogamous relationships are usually advised to use condoms.

Discussions of safe sex during menstruation often include pregnancy. Some people may be under the impression that they need not worry about pregnancy during menstruation. The truth is, however, that it is possible for sperm that enters the body during menstruation to survive long enough to impregnate a woman. Though not likely, it is even possible for an egg to be released while a woman is still having vaginal bleeding.