The menstrual cycle can vary from woman to woman -- and teen to teen -- though most menstrual periods do not last longer than a week. In some cases, prolonged periods could be a symptom of another medical problem. If you suspect that your daughter's menstrual cycle is abnormally long, contact her doctor for an appointment.
Beginning of Menstruation
While it is commonly believed that a girl's period begins 28 days after the first day of her last period, the first few years of menstruation tend to be unpredictable, says KidsHealth.org. During the first three years of menstruation, teenage girls may have periods more often than expected or may have periods lasting longer than a week. This is typically not cause for a concern. If your daughter is concerned she is bleeding too heavily, a doctor can run tests for anemia and prescribe iron supplements if necessary. If your daughter's period is still prolonged three years after she started having periods, she should see her doctor.
Birth Control Side Effects
If your daughter is using hormonal contraceptives, it may be causing her to have prolonged periods, says Boston Children's Hospital. Switching to a different type of birth control pill, or switching to a different method like the patch or ring, may cause her periods to return to normal. If prolonged bleeding continues even when she switches to a different pill, she may want to use other forms of contraception.
Hormones and Infections
Prolonged or heavy periods may be the result of an imbalance between estrogen and progesterone in your daughter's body, says KidsHealth.org. A teenager's doctor can prescribe medications to handle this imbalance. Other problems, such as vaginal or cervical infections or a problem with the thyroid, could also be to blame for prolonged periods. Your daughter can schedule an appointment with her doctor for an exam and treatment for the underlying cause of her prolonged periods.
Von Willebrand Disease
Bleeding disorders like Von Willebrand disease can cause heavy and prolonged periods in teenage girls, according to MayoClinic.com. Teenagers who have this disease may notice that their periods are prolonged as soon as they begin having them. Doctors may prescribe patients medications or oral contraceptives to reduce menstrual symptoms. Some women who have Von Willebrand disease don't need any treatment if their symptoms are mild.