In 4% of cases the patch can come off the skin before the week is over – if this happens unnoticed, you may not be as well protected against pregnancy.
Up to 48hrs without a patch – try to put it on again or put on a new patch immediately. Your 'patch change day' will stay the same. Do not try to replace the same patch if it's no longer sticky, is stuck to something else, or has already fallen off once before.
More than 48hrs without a patch or the time detached is uncertain - start a new patch immediately. You now have a new 'day 1' and patch change day. Use condoms for the next 7 days. You may need to take additional emergency contraception if you have had sex within the previous 5 days.
More than 24 hours late after a 7 day patch-free break – Apply a new patch immediately. Keep the new patch on until the day you usually change it. If you had unprotected sex during the patch-free break, you might need emergency contraception now and a pregnancy test in 3 weeks.