I'm 19 years old and my period has been irregular since I first got it. I've had it for 5 years now. Is this normal?
- Clare*

It is normal to have irregular periods for the first few years of menstruating — and sometimes even longer. But the only way to know if everything's OK is to visit your doctor or nurse practitioner.

A number of things can cause irregular periods. A girl may have something going on with her hormones, for example. And excessive exercise, not eating enough calories, or being underweight or overweight can also affect a girl's menstrual cycle. So can medications or drugs (like steroids).

Since you've had irregular periods for more than 3 years, see your doctor or nurse practitioner to find out what's causing them. He or she may be able to prescribe medications to help correct a medical problem. Or, if things like exercise or eating habits are behind your irregular periods, a lifestyle change may be recommended.

Girls who are having sex (or have had sex in the past) should get a gynecologic exam. Pregnancy or sexually transmitted diseases (STDs) can also affect a girl's periods — and some STDs can cause serious long-term complications, such as infertility.

Reviewed by: Larissa Hirsch, MD
Date reviewed: March 2011

*Names have been changed to protect user privacy.