Here's more information on Yaz:
http://www.medhelp.org/drugs/Yaz/show/3391
If you click the "Uses" tab, you'll see a section called, "What happens if I miss a dose of drospirenone and ethinyl estradiol?".
From Drugs.com:
What happens if I miss a dose?
Missing a pill increases your risk of becoming pregnant.
If you miss one"active" pill, take the dose as soon as you remember or take two pills at the time of your next regularly scheduled dose. You do not need to use backup birth control.
If you miss two"active" tablets in a row in week one or two, take two tablets each for the next two regularly scheduled doses (one missed tablet plus one regularly scheduled tablet for 2 days in a row). Use another form of birth control for at least 7 days following the missed tablets.
If you miss two "active" tablets in a row in week three, or if you miss three tablets in a row during any of the first 3 weeks, throw out the rest of the pack and start a new package on the same day if you are a Day 1 starter. If you are a Sunday starter, keep taking a pill every day until Sunday.
On Sunday, throw out the rest of the pack and start a new pack of pills that same day. You may not have a period that month, but this is expected. However, if you miss your period 2 months in a row, call your doctor because you might be pregnant.
If you miss one of the reminder pills in week four, skip that dose and take the next one as directed.
If you miss a pill, you may become pregnant if you have sex in the 7 days after your missed pill. You MUST use another birth control method (such as condoms or spermicides) as a back-up for those 7 days.
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If you don't know what else to do (these instructions are tricky!), keep taking your pills and use a back up method until you can talk to your health care provider.