[escape_thereal_world]

"This isn't the case, though some women will experience bleeding after taking Plan B. Trussell describes it as “not rare” but also “not common.” The bleeding is called a “withdrawal bleed” and is not menstruation. Rather, it’s caused by the change in hormone levels."

You can read more here about Plan B.

Though, Lynds is right that Plan B isn't 100% effective. It's most effective if taken immediately after intercourse. The more time that passes, the less likely it is to work. So, I'd advice taking a pregnancy test in a couple weeks or whenever you actual period is due to be certain.