4 doctors weighed in:
What is the difference betwee28n 21 day birth control pills?
4 doctors weighed in

Dr. Peter Corrado
Family Medicine
3 doctors agree
In brief: Not much
Both types have 21 active pills taken during the first three weeks of your cycle.
The extra 7 pills in the 28 pill pack are inactive. When the 21 pill pack runs out, you wait 7 days then start a new one. With the 28 pill pack you start a new pack as soon as the old one runs out. It both cases menses occur during the 4th week due to hormone withdrawal.

In brief: Not much
Both types have 21 active pills taken during the first three weeks of your cycle.
The extra 7 pills in the 28 pill pack are inactive. When the 21 pill pack runs out, you wait 7 days then start a new one. With the 28 pill pack you start a new pack as soon as the old one runs out. It both cases menses occur during the 4th week due to hormone withdrawal.
Dr. Peter Corrado
Dr. Peter Corrado
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