How many days does implantation bleeding last?

According to Mayo Clinic, implantation bleeding lasts for a short time and may not even be noticed. However, it can also be mistaken for a menstrual cycle.

Implantation bleeding is thought to occur when the fertilized egg implants in the uterus lining. It usually occurs about 10 to 14 days after conception. Implantation bleeding is usually a discharge that is brown or light colored and has no clots. This is considered normal. WebMD states that up to 25 percent of pregnant women experience some form of vaginal bleeding or spotting. A woman should seek medical attention if the bleeding turns bright red or becomes heavier.