Is it permissible for a menstruating woman to enter the Haram in Medina, and what should she do if she is menstruating in Medina?

A menstruating woman is not prohibited from entering Makkah or Madinah. The sacred texts do not forbid this; rather, they indicate the opposite. An example is the incident involving 'Aisha (may Allah be pleased with her) during the Farewell Pilgrimage, when she menstruated before entering Makkah. The Prophet (peace be upon him) did not prevent her from entering it; instead, he commanded her to perform all the rituals of Hajj except for circumambulating the Kaaba until she became pure. Similarly, women residing in Madinah experience menstruation and do not leave the city. However, it is not permissible for a menstruating woman to enter a mosque (whether the Sacred Mosque, the Prophet's Mosque, or any other).