Pills 1354782 1920When it comes to contraception, the pill remains the best thing since — well, the condom. By taking birth control regularly, you can take family planning into your own hands, whether you’d like to postpone parenthood or skip it all together. One common question I hear from my patients is “when does birth control start working?” 

I was recently interviewed by Popsugar on this topic which, for me, highlighted the importance of the timing and spacing conversation. This common inquiry reflects both the thought and concern involved in spacing. 

Spacing is the term used amongst women’s health professionals to refer to intentionality around pregnancies. If spacing is your reason for adding a tiny-tablet routine, there are a few factors to take into consideration before saying goodbye to your old rubber (or latex) friend.

When does birth control start working?

All birth control pills use hormones to create changes in a woman’s body in order to prevent its ability to become pregnant 99% of the time (if taken correctly). But despite the common features across birth-control types, the answer to the question “when does birth control start working?” depends on two factors:

  1. Where you are in your cycle 
  2. What form of birth control you take 

Progestin-only pills

Progestin-only birth control contains the hormone progestin, which thickens cervical mucus, making the ability of the sperm to reach an egg almost impossible. This type of pill also works to prevent ovulation. For that reason, you will have immediate protection if you begin progestin-only contraception within the first five days of starting your period. If you begin taking this form of birth control at any other point in your cycle, allow 48 hours before removing additional forms of birth control.

Combination pills

Combination pills require a bit more consideration. They contain two types of hormones that prevent ovulation. If you start taking a combination pill within 5 days of starting your period, protection is immediate (just like with progestin-only pills). However, if you begin at any other time in your cycle, the combination pill will require a full week (7 days) of use before becoming fully effective.

Exceptions to the rules

Please keep in mind that the beauty and wonder of the female body are its unique differences from woman to woman. Pills are synthetic hormones that interact with our natural hormones to manipulate the body’s ability to become pregnant. The timing rules outlined above are based on starting at a given time in a typical 28-day menstrual cycle. For women who aren’t “regular”, timing is based on the hormone shifts specific to their unique cycle. 

For example, women taking the progestin-only pill with cycles shorter than 23 days should never assume the pill will take immediate effect and should always wait a full 48 hours. 

If you’re a play-it-safe type of “spacer”, give yourself 5 days on progestin-only pills and 7 days on combination pills before eliminating your secondary form of birth control.

Digestive disorders can also have an impact on the effectiveness of birth-control pills. Conditions like Crohn’s Disease, Irritable Bowel Syndrome and even a bad case of food poisoning can have an impact. With serious diarrhea or vomiting, our body’s ability to absorb any oral medication correctly is limited. If you’re dealing with chronic issues, talk to your healthcare provider to see if another form of birth control is warranted. In general, if you experience vomiting and/or diarrhea for more than two days you should act as though you missed a pill and plan accordingly.

Remember the limitations of birth control

While birth control pills are a fantastic way to gain control over the timing or avoidance of pregnancies, it’s important to remember that they don’t protect you against STDs or STIs. The best way to prevent contraction of sexually transmitted diseases is to use a condom every time you have sex. So it might be time to re-acquaint yourself with that old latex pal after all. 


Meet Dr. Savita Ginde

Dr. Savita Ginde is a crusader and thought leader for reproductive health and has served as Vice President and Medical Director of Planned Parenthood of the Rocky Mountains for over 14 years.  Read More»