-- Posted by bengals25 at 10:27 pm on July 2, 2009 how effective is birth control if not taken on the same exact time period just a couple hours off ? -- Posted by blackbandaid at 10:28 pm on July 2, 2009 Depends on which pill it is. Some don't matter. Others will render the BC invalid until 7 days of correct usage pass. -- Posted by See Me Now at 10:29 pm on July 2, 2009 Well, I don't think an hour or two is bad, but more than that is definitely not good territory. Just set an alarm, and take it at the same time every day. -- Posted by JennyColada at 5:21 am on July 4, 2009 Under "regular use" I think it's about 95% reliable at preventing pregnancy.