Someone asked us:

Q. Why should birth control pills be taken at the same time every day? What are possible consequences of taking them at varying hours, but still daily?

The world of birth control pills can pretty much be split into two categories: combination pills and progestin-only pills. Combination pills get their name from the fact that they use two different hormones — estrogen and progestin — to prevent pregnancy. Most people on the pill take combination pills. Progestin-only pills contain — you guessed it — just progestin.

What does this have to do with the time you take your pill? Progestin-only pills need to be taken at the same time every day, in order for them to work. If you take a progestin-only pill more than three hours past the regular time, you need to use a backup method of birth control (like a condom) for the next 48 hours. Combination pills, on the other hand, give you a little more leeway. It’s only essential that you take the pill every day. But taking the pill at the same time every day can still make it more effective. That’s because most people are more likely to remember to take the pill if they make it a regular part of their routine.

So if you’re on the combination pill, and you take your pill at 9 AM one day and 1 PM the next, you’ll be okay. But making your pill-time a constant in your schedule — like taking it when you brush your teeth or wake up in the morning — is still a good idea, since it makes forgetting a pill less likely.