Abnormal uterine bleeding is when periods:

• are very heavy or very light
• last longer or shorter than normal (longer than 8 days or shorter than 4.5 days)
• come more or less often than expected (more than every 24 days or less than every 38 days)

Girls who have very heavy bleeding or more frequent periods can get anemia (too few red blood cells). 

If needed, there are ways to treat abnormal uterine bleeding. Help your daughter follow these instructions.

• Help your daughter track her periods on a calendar or a smartphone app. She should include:
  • when her period starts and ends
  • the amount of flow each day
  • whether there are any blood clots
  • whether she has cramps or other problems during her period
• Depending on the cause of your daughter's abnormal uterine bleeding, the health care provider may recommend that your daughter:
  • Wait and see if her periods become more regular. 
  • Manage stress by getting enough sleep and plenty of exercise, avoiding drugs and alcohol, and doing things that are relaxing for her such as listening to music, yoga, or meditation.
  • Take medicines that can balance hormones, such as the birth control pill ("the Pill"), or use a birth control shot, a birth control implant, or an IUD.
  • Lose or gain weight through changes in diet and exercise.
  • See a doctor who specializes in women's health (a gynecologist) or other specialist for more testing. 
• Fill any prescriptions and be sure your daughter follows the health care provider's recommendations for taking medicines.
• Girls with abnormal uterine bleeding can still get pregnant if they have sex. Talk to your daughter about using condoms to protect against pregnancy and sexually transmitted infections (STIs, also called sexually transmitted diseases or STDs).
• Call the health care provider or log in to your daughter's electronic health record (EHR) to get any test results.
• Follow up as instructed by your health care provider.

Your daughter:

• has periods that last longer than 8 days or shorter than 4.5 days 
• has very heavy periods that soak through a pad or tampon every hour
• gets a period more than every 24 days or less than every 38 days
• has bleeding between periods
• got her first period more than 2 years ago and still has irregular periods
• has signs of anemia, such as having headaches or being tired, pale, or dizzy

What causes abnormal uterine bleeding? Abnormal uterine bleeding in teens is most often caused by:

• changing hormone levels in the first few years after a girl starts getting her period
• hormone problems from medical conditions such as polycystic ovary syndrome 
• being overweight or underweight
• intense exercise
• stress
• fibroids or other growths in the uterus
• medical conditions that cause easy bleeding
• some medicines, including the Pill; also a birth control shot, a birth control implant, or an IUD
• pregnancy
• infection, including STIs