It's not common, but Plan B can lead to unexpected spotting and bleeding. According to the package insert, Plan B can cause other changes to your period, such as heavier or lighter bleeding or getting your period earlier or later than normal.

When should I worry about Plan B bleeding?

In the weeks after taking Plan B, light spotting between periods or a heavier flow are not typically a cause for concern. However, if these issues do not go away within a month or so, something other than Plan B may be responsible.

What does it mean if you bleed after Plan B?

Some irregular bleeding — also known as spotting — can happen after you take the morning-after pill. Getting your period after taking emergency contraception (EC) is a sign that you're not pregnant. It's also normal for your period to be heavier or lighter, or earlier or later than usual after taking EC.