Progestin-only Pills (POPs)

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What are POPs?

The progestin-only pill differs from combined oral contraceptives in that it contains only one hormone, called progesterone. (The combined pill contains both estrogen and progestin.)

How do POPs work?

There are many ways in which progestin-only pills work: they thicken cervical mucus; decrease ovulation (the release of an egg) or fertilization; and change the lining of the fallopian tubes and uterus. To be most effective, these pills must be taken every day at the same time. There are no ‘reminder’ pills to take, and there are no days you don’t take pills. As with other progestin-only methods, irregular bleeding is common.

How effective is it?

About 3 women in 100 using the progestin-only pill perfectly for one year will get pregnant. In actual use, 8 women in 100 using POPs will get pregnant in one year.

Could I have problems taking it?

You could have irregular bleeding, and you risk pregnancy if you take your pill three hours late or more and have sex during the next 48 hours.


  • No estrogen

  • Lighter to absent bleeding, less cramping and PMS

  • Decreased risk of uterine and ovarian cancer.

  • May decrease symptoms and possibly treat endometriosis.


  • Have to remember to take a pill everyday at exactly the same time

  • Does not protect against sexually transmitted infections

  • Irregular bleeding

How do I use it?

  • Each pill package contains 28 pills. Every pill contains hormones; there are no ‘reminder’ pills. POPs must be taken daily without interruption to be effective, because the small amount of progestin in them is used rapidly in the body. Little or none of it remains in the body after 24 hours.

  • It’s essential to take your pill at the same time every day.

  • You can start POPs at any time during your cycle. If you start on the first day of your period, you don’t need a back-up contraceptive method. If you start later, use a back-up method for 48 hours afterward.

  • When you first start POPs, as your body gets used to them, you could have minor side effects like ‘breakthrough’ bleeding and headaches. They’re not dangerous and usually go away in the first two months. If you have symptoms that persist longer, or seem severe, call or return to the clinic for a re-evaluation. About half the women who take POPs have irregular bleeding—irregular bleeding doesn’t mean your pills aren’t working

What do I do if I miss a pill?

  1. If you miss a pill by 3 hours or more, take it as soon as you remember, and for the next 48 hours use a back-up method like condoms, or don’t have intercourse. Continue taking your pills at the regular time, even if that means taking 2 pills in one day.

  2. Use a back-up method for 48 hours after any episode of heavy vomiting or diarrhoea, because illness may cause you to absorb too little of your pill to be effective.

  3. If you have unprotected sex after missing a pill by 3 or more hours, you can get emergency contraception, provided you do so within 120 (5 days) hours for best results. Continue taking your pills, but talk to your clinician as soon as possible. Consider having a pregnancy test two to four weeks after taking ECP just to be certain you aren’t pregnant.

  4. If you accidentally become pregnant while using POPs, your fetus won’t be harmed by the small amount of progestin in the pills. However, as with any other medication, discontinue use as soon as you know you’re pregnant.

What do I do if I miss a period?

If you don’t get a period within 45 days of your last one, call the clinic for a pregnancy test. Continue your pills until your appointment. Many women on POPs have irregular spotting or bleeding and some do not have a period at all.

What happens if I stop taking POPs?

Your first period may be irregular or it may be late. It’s possible to get pregnant soon after discontinuing POPs. If you don’t want to be, use another birth control method.

What else should I know?

  • Always tell your doctor if you’re using the progestin-only pill.

  • Some medications, like those for seizures, tuberculosis, and diarrhoea and vomiting, can lower the effectiveness of the pill so that you could become pregnant even if you don't miss any pills. While on these medications or when you’re sick, use another method of birth control like foam and condoms along with your pills, or you may need to discontinue them temporarily for another method.

  • If you have an emergency when the clinic is not open, call your family doctor or go to the local hospital emergency room.

  • If you have any questions or problems, call your clinic or the SEX SENSE line at 1 800 SEX SENSE .


Revised March 2009