Plan B can cause spotting, early periods and late periods. The dark, almost black blood is probably spotting. At this point, three weeks after taking Plan B, you may want to take a pregnancy test. You can do one at home or schedule an appointment at the SHCC for a pregnancy test and contraception counseling. Plan B has been found to be 87% to 98% effective in preventing pregnancy. Pregnancy rates increase in delay in starting treatment, within 24 hours it has only a 1.17% failure rate. Pregnancy rates also increase if further acts of unprotected intercourse took place after treatment.
