Will taking progesterone induce menstruation?

Taking progesterone can induce menstruation, but it must be administered in sufficient dosage under a physician’s guidance; otherwise, it will not be effective. Moreover, menstruation does not occur immediately after taking progesterone—rather, it typically begins 7–10 days after completing the course of medication. In some women, menstruation may commence as early as two days after starting progesterone, primarily because their endometrium has already reached an adequate thickness. In such cases, menstruation would occur spontaneously regardless of progesterone administration; it is not induced by the progesterone itself.