How long do you have to take birth control to regulate periods?

Three months: You should see an effect on the amount of bleeding you have within the first cycle however I would give it a full three months before making any assessments on how much you like or do not like the results. A Mirena (levonorgestrel) iud however would be the best for control of irregular bleeding.

Depends on problem: The answer depends on the individual and the underlying cause of irregular menstrual cycles. Polycystic ovarian syndrome is the most common cause. Taking pills regulates the cycle but does not address the underlying problem.

2 or 3 months: Oral or hormonal IUD forms 1 to 2 months. Progesterone injections 3 or more months.