Progestin-only contraceptives

Progestin-only birth control pills, also known as small pills, are a type of oral contraceptive (birth control pill). Each progestin-only pill contains a small amount of progestin (the synthetic form of progesterone). These pills do not contain any estrogen.


Progestin-only birth control pills prevent pregnancy primarily by changing the consistency of cervical mucus. Progesterone thickens your mucus, which makes it harder for sperm to pass through.

Small pills can also work by thinning the lining of the uterus. This will reduce the likelihood of implantation. Progestin-only pills may also prevent you from ovulating (which is the case in about half of the women who use them).


Because the small pills contain less progesterone than combined birth control pills, the effects of progesterone on cervical mucus only last about 24 hours. That’s why it’s important to take progestin-only pills at the same time each day.

If you miss a dose of progestin-only birth control pills for more than 3 hours, you will need to use a backup birth control pill (such as a condom) or avoid intercourse until you have taken the pill correctly and on time for 2 consecutive days.

Having said that, the progestin-only birth control pill is a very effective birth control pill. Minipill is 91% to 99% effective. This means that under typical use, 9 out of 100 women will become pregnant within the first year of use.

READ ALSO:  Explaining birth control failure rates

Before taking

Because mini-pills do not contain estrogen, they are a great option for women who cannot use combined hormonal contraceptives.

Contraindications to the use of estrogen include:

  • Smokers over the age of 35.
  • Women with a history of thrombosis.
  • women with high blood pressure.
  • Women with extreme migraine or migraine with aura.

Mini Pills and Breastfeeding

Progestin-only contraceptives may be prescribed to breastfeeding mothers, as progestins do not negatively affect milk production or harm the breastfed baby.

Precautions and contraindications

Women who should not take small pills include:

  • active liver disease
  • undiagnosed vaginal bleeding
  • Breast cancer, known or suspected
  • pregnant, known or suspected


Traditionally, minipills are only available in 28-day packs. All 28 pills contain progestin (no placebo pills). You take one pill a day for 4 weeks (packet). This way, you will get a steady dose of hormones.

The latest formulation of the progestin-only pill (drospirenone 4 mg) has 24 active pills and 4 pills without any hormones. You should take each pill at the same time each day.

You may have periods while you are still taking the “active” pill. If your menstrual cycle is usually 28 days and you start taking progestin-only birth control pills on the first day of your cycle, you will most likely get your period in the first week of your next pack.

Only about 50% of women who use minipill ovulate regularly, making it difficult to predict when your period will occur. Progestin-only birth control pills will not regulate your cycle like combined birth control pills.

Progestogen only and combination drugs

Although both pill types are considered hormonal contraceptives, there are some differences between the two to be aware of.

Progestin Only Pills

  • Contains less progesterone than compound pills

  • slightly less effective

  • fewer side effects

  • Must be taken at the same time every day

Compound pill

  • Contains more progestin than progestin-only pills

  • slightly more effective

  • more side effects

  • some flexibility in the time of day

amount of progesterone

A typical progestin-only pill contains 0.35 milligrams (mg) of norethisterone or 4 mg of drospirenone. A typical combination pill contains 0.4 mg or more of norethisterone and 3 mg of drospirenone. The amount of progestogen in a progestin-only pill is lower than the dose of progestogen in a combined birth control pill.


Progestin-only birth control pills are slightly less effective than combined birth control pills.

side effect

Unplanned bleeding is the most common side effect of progestin-only pills and the biggest reason for discontinuation. Other side effects may include acne, mood changes and weight gain.

easy to use

Some women say progestin-only birth control pills are harder to use than combination pills.This is because progestin pills must be at the same time every day. Because combined birth control pills are made up of progesterone and estrogen, you’ll have more flexibility if you don’t take the pill at the same time.

Frequently Asked Questions

  • Are you still taking mini pills?

    Yes, you will still have periods when you are using progestin-only birth control pills. Some women also experience breakthrough bleeding or spotting throughout the month.

  • Are mini pills less effective than regular birth control pills?

    Yes, but only slightly. Progestin-only birth control pills don’t always prevent ovulation as well as combination pills. Therefore, they have a slightly higher failure rate in typical use.

  • Do Mini Pills Cause Weight Gain?

    possible. Weight gain is a common complaint among women taking hormonal contraceptives. However, studies have shown that mini-pills have little effect on body weight. A Cochrane review of 22 studies found that women who used progestin-only contraception gained an average of 4 pounds over a 12-month period.