Contraception: the mini (progestogen-only) pill

What is the mini pill?

The mini pill or progestogen-only pill (POP) is a type of contraception that you take as tablets. It contains a low dose of the synthetic hormone progestogen, which mimics progesterone - one of the natural female sex hormones. The progestogen in the mini pill works in several ways to prevent you from getting pregnant.

Unlike the combined oral contraceptive pill, the mini pill does not contain any oestrogen - hence the name progestogen-only.

Brands of mini pill available in Australia include Microlut Tablets (which contain a progestogen called levonorgestrel), and Noriday 28 Tablets (which contain a progestogen called norethisterone).

How does the mini pill work?

The mini pill works mainly by thickening the mucus in the vagina and cervix (lower part of the uterus, or womb). The thicker mucus makes it very difficult for the sperm to get through the entrance of the uterus to fertilise an egg.

It also thins the lining of the womb, which makes it difficult for an egg to implant even if it does become fertilised.

The mini pill may sometimes help prevent the release of eggs from the ovaries. However, the mini pill does not reliably suppress ovulation.

Effectiveness at preventing pregnancy

The effectiveness of a contraceptive method can be measured for perfect use and typical use.

  • Perfect use is when instructions are followed precisely. The failure rate for perfect use of the mini pill is about one per cent. So if used perfectly, about one woman in every 100 will become pregnant in a year.
  • Typical use is what tends to happen in reality. Typical use failures include failures due to incorrect use. The failure rate for the mini pill is about 8-9 per cent in a year of typical use.

The mini pill tends to be less effective in younger, more fertile women than in older women.

Advantages of the mini pill

Some of the advantages of the mini pill:

  • It may be suitable for women who cannot take the combined pill because of the oestrogen it contains. For example, those with heart disease, high blood pressure, a history of stroke, those at risk of blood clots, and women who experience certain types of migraine headaches.
  • It can be used when you are breast feeding.
  • It doesn’t interfere with sexual spontaneity.
  • It allows fertility to return without delay after you stop taking it.

Disadvantages

Some of the disadvantages of the mini pill:

  • It must be taken at the same time every day.
  • It is less effective than the combined pill as a contraceptive.
  • It is only available on prescription.
  • It may result in spotting or irregular vaginal bleeding.
  • It does not protect against sexually transmitted infections (STIs).
  • It is not recommended for women with certain medical conditions (including severe liver disease or a history of breast cancer).
  • It may not be suitable for women taking certain medicines (such as medicines to prevent seizures, St John’s wort or certain antibiotics).

How is it used?

The mini pill should be taken on a daily basis, at the same time each day. The tablet should be swallowed whole. It makes no difference if you take it before or after eating.

You need to be meticulous about taking it at the same time every day for it to be effective. In some women, the effect of the mini pill can wear off after about 21 hours. So when choosing the time of day that you take the mini pill, take into account the time when you are likely to usually have sex. If you tend to have sex in the evening, take your mini pill in the morning.

You take the mini pill continuously - there are no inactive (sugar) pills like with the combined oral contraceptive pill, and you don’t need to take a break between packs of pills. Continue taking the mini pill every day, even when you have a period.

Starting the mini pill

If your doctor has prescribed the mini pill, you can usually start taking it straight away. Often the best time to start is on the first day of your period. It’s usually recommended that you use another form of contraception (such as condoms) for the first 2 to 7 days as a backup. Check with your doctor about how long to use backup contraception.

If you have been using another type of hormonal contraception, have just had a baby, are breast feeding, or have just had a miscarriage or abortion, check with your doctor whether you need to wait before starting the mini pill.

What to do if you forget a pill

If you forget to take a pill but it is less than 3 hours late, simply take the missed pill when you remember, and continue taking the mini pill as usual.

If it is more than 3 hours late, take the missed pill as soon as possible. Take the next pill at the usual time, even if that means taking 2 pills in one day. Alternative contraception (such as condoms) should be used until at least 3 pills have been taken at the usual time.

Contact your doctor, pharmacist or local Family Planning Clinic about whether you need another form of protection against pregnancy.

What to do if you have vomiting or diarrhoea

If you have vomiting or severe diarrhoea, you may not absorb the mini pill, and therefore may not be protected against pregnancy. You should use an additional method of contraception (such as condoms) until you get your next period.

Women who should not take the mini pill

Some women should not take the progestogen-only pill because the risks of taking it outweigh the benefits.

Women who have had breast cancer in the last 5 years should not take the mini pill. Doctors also recommend that women with liver disease, unexplained vaginal bleeding, heart disease, stroke or blood clots do not take this form of contraception.

Medicines that may interfere with the mini pill

Some prescription and complementary medicines should not be taken while you are on the mini pill because they can reduce its effectiveness. These include:

  • some medicines that are used in the treatment of epilepsy;
  • certain antibiotics and antifungal medicines; and
  • a herbal preparation called St John’s Wort.

Antacids may affect the absorption of the mini pill, so don’t take them for 2 hours before or after taking the mini pill.

The mini pill may also interact with other medicines, including antiviral medicines used in the treatment of HIV/AIDS and hepatitis C. Your doctor can advise you about which medicines are safe to take while you are taking the mini pill.

Side effects of progestogen-only contraception

The most common side effect associated with use of the mini pill is irregular menstrual bleeding. This may include more or less frequent periods, lighter periods or spotting between periods. In a small number of women, periods may stop altogether. This side effect usually gets better within about 3 months of using the mini pill.

Less common side effects, which also usually improve after a few months, include:

  • breast tenderness;
  • possible mood changes;
  • headaches;
  • bloating;
  • acne;
  • decreased or increased libido (sex drive); and
  • nausea.

Some women develop small cysts on the ovaries after taking the mini pill. This is rare, and the cysts usually go away on their own without any treatment. They usually do not cause symptoms, but some women have pain.

Visit your doctor or Family Planning Clinic if you think the mini pill might be a suitable form of contraception for you.

References

1. Progestin-only contraception (published March 2014). In: eTG complete. Melbourne: Therapeutic Guidelines Limited; 2017 Mar. https://tgldcdp.tg.org.au (accessed May 2018).
2. Family Planning Victoria. The mini pill (updated 5 Jun 2016). https://www.fpv.org.au/for-you/contraception/daily-contraceptive-pills/the-mini-pill (accessed May 2018).
3. NHS Choices. The progestogen-only pill (updated 8 Jan 2018). https://www.nhs.uk/conditions/contraception/the-pill-progestogen-only/ (accessed May 2018).
4. Mayo Clinic. Minipill (progestin-only birth control pill) (updated 2 Mar 2018). https://www.mayoclinic.org/tests-procedures/minipill/about/pac-20388306 (accessed May 2018).
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