The minimum interval of purity between two menstrual cycles is thirteen days; its usual length is the rest of the month, and there is no upper limit.1

Menstruation makes a number of matters unlawful: among them are vaginal intercourse, issuing a divorce, performing the prayer, and fasting,2 circumambulating the Kaʿba, reciting the Quran, touching the mushaf, remaining in the mosque, and even passing through it if she fears staining it.

Intercourse during menstruation obligates ghusl, bulugh (full penetration), and the payment of an expiation,3 even if the man was coerced, forgetful, or unaware of the bleeding or its prohibition. The compensation is one dinar or half a dinar, at his discretion,4 and the same applies to her if she consented.

After the bleeding stops, but before she performs ghusl or tayammum, nothing becomes permissible except fasting, issuing a divorce, and remaining in the mosque provided she is in a state of wudu.

The cessation of bleeding is determined when a cotton pad inserted during the time of menstruation comes out without any discoloration; at that point she is considered pure.

A menstruating woman and a woman experiencing post-partum bleeding must make up their missed fasts, but not their prayers.