Dysfunctional uterine bleeding is irregular vaginal bleeding that is not caused by a serious medical condition.

Normally one of your ovaries releases an egg during your menstrual cycle. This is called ovulation. Most women who have dysfunctional uterine bleeding get it when their ovaries don't release an egg. This can be caused by hormone changes. When your hormone levels are out of balance, they can affect the lining in your uterus, causing bleeding. Dysfunctional uterine bleeding is common before age 20 and after age 40.

Some women have dysfunctional uterine bleeding even though they ovulate. Experts don't fully understand this type of vaginal bleeding. It may be caused by changes in certain body chemicals.¹

For more information about serious causes of vaginal bleeding problems, see the topic Abnormal Vaginal Bleeding.