How long does breakthrough bleeding usually last?

Spotting to 2+ wks..: It is variable, but typically breakthough bleeding last 2-3 days. Some unfortunately can last couple of weeks...Often lighter and less crampy than normal menstrual flow. So, if you have prolonged and heavy flow with significant pain/fever etc...Please consult doc for possible infections such as endometritis etc... Good luck.

Varies: Breakthrough bleeding is common but not normal therefore there is no normal time for it to last.