What is the medicine to have regular menstruation?

Maybe OCP's: Oral contraceptives (ocp's) may help in some cases. However, you need an evaluation first to see why you aren't having regular menstrual periods already. For this, please see your family doctor or your gyn physician.

See answer: Discuss with your gyn, but generally speaking, the daily birth control pills can often regulate your cycle as well.

Unclear your ?: Are you asking what medication can one take in order to provoke a menstruation? Or what medication can help regulate a menstrual cycle. The answer to the former is Progesterone or provera (medroxyprogesterone). The answer to the latter is birth control pills, either estrogen and progesterone, or solely progesterone.