When does the birth control pill become effective?

Yes. You are on your period that means that ovulation would have all ready happened and since you are on the pill it didn't happen, so you are safe. Only if you start missing days and days of your pill will you get pregnant .

No. There is no interruption in protection when you change from one pill to another, no matter what the change. In addition, TriSprintec and Tricyclen are equivalent, with the same ingredients at the same strength. Your body doesn't know you cahnged from the brand to the generic.

Regardless of the birth control pill you are taking, per FDA guidelines and standard GYN practice:

  • If you start the pill in the first five days of menstrual bleeding, no backup method is needed.
  • If you start the pill at any other time in your cycle, use a backup method of birth control, like condoms or abstinence from vaginal sex, for the first seven days of that first pack.

You can confirm this information by checking the FDA insert that came with your birth control pill, or by calling your prescriber or pharmacist.

For reasons of patient error, some health care providers recommend that new users, particularly teens, use a back up method for a month because of the increased possibility of missing a pill, not because the pills, when taken as directed, take that long to start to work.

In other countries, patient package inserts may differ. For instance, a link to prescribing information for Diane 35 and Diane 35 ED lists three different rules for timing of effectiveness in the same package insert. See link below for full information.

Regardless of the birth control pill you are taking, per FDA guidelines and standard GYN practice:

  • If you start the pill in the first five days of menstrual bleeding, no backup method is needed.
  • If you start the pill at any other time in your cycle, use a backup method of birth control, like condoms or abstinence from vaginal sex, for the first seven days of that first pack.

You can confirm this information by checking the FDA insert that came with your birth control pill, or by calling your prescriber or pharmacist.

For reasons of patient error, some health care providers recommend that new users, particularly teens, use a back up method for a month because of the increased possibility of missing a pill, not because the pills, when taken as directed, take that long to start to work.

In other countries, patient package inserts may differ. For instance, a link to prescribing information for Diane 35 and Diane 35 ED lists three different rules for timing of effectiveness in the same package insert. See link below for full information.


30 days. One complete pill cycle.