Women who are menstruating should assume ihram after a bath and recite talbiyah and engage in dhikr and du`aa’. However, they must not offer Prayer. They can practice all of the rituals of Hajj with the sole exception of Tawaf.
Dr. Rif`at Fawzi, Professor of Shari`ah at Cairo University, states the follwoing: There is nothing wrong, as far as Islam is concerned, if a woman takes such pills during Hajj in order to be able to continue performing Hajj without interruption.

However, we have to keep in mind that a woman is allowed to do so while being guided by the following conditions:
1- Taking such pills must not result in putting her life and health at stake, based on the Hadith: “Let there be no harm or reciprocating harm”.
2- It is better, before taking such medication, to seek the advice of a reliable physician.