Family doctor



THE MINI PILL - a patient's guide


The mini pill is a useful alternative for women who cannot use the combined oral contraceptive pill. This article provides advice on how it is used and common side effects.

mini pill


  • The mini pill is also known as the progestogen-only pill
  • Unlike the combined pill, it does not contain the hormone oestrogen
  • The mini pill has fewer side effects than the combined pill
  • It must be taken at the same time each day to be effective.
  • The mini pill is taken every day without any breaks

What is it?

The mini pill is also known as the progestogen-only pill because it only contains the hormone progestogen. It does not have any oestrogen such as the combined oral contraceptive pill and has a lower dose of progestogen.

The mini pill is often prescribed to women who are breastfeeding because it does not affect the supply of breast milk. It is also a popular choice for women over 35 because it has fewer side effects.

The mini pill works by altering the cervical mucous, which makes it a lot harder for sperm to reach the uterus and fallopian tubes where fertilisation normally occurs. It also makes it harder for a fertilised egg to implant in the lining of the uterus. Unlike the combined pill (containing oestrogen), the mini-pill does not prevent ovulation.

The mini pill has a failure rate of 4 percent with normal use. However, it is as low as 0.5 when used perfectly. The combined pill has a failure rate of between 0.1 to 3 percent.

The most common reason for an accidental pregnancy on the mini pill is missing a pill.

How is it used?

Your blood pressure must be checked before the mini pill is prescribed.

Follow the instructions in the pill packet.

It is generally recommended that you start your first pill packet when your period begins (on the first day), this is to ensure you are not already pregnant. If your period is irregular, or there is any doubt, a pregnancy test should be done first.

If you are using the mini pill while breastfeeding, you may be recommended to wait until your baby is six weeks old before starting the pills.

The mini pill MUST be taken at the same time each day to be fully effective. Even if it is taken three hours late you may not be protected against pregnancy.

One pill is taken each day. There is no seven-day break when taking the mini pill, unlike the combined pill where you take active pills for three weeks and have a 1-week break.

Missed pills

If you are less than three hours late taking a pill, take it immediately and you will still be protected. Continue taking the rest of the pills as normal.

If you are more than three hours late taking a pill you must take the most recent pill in your packet and then follow the "seven-day" rule. This means using another form of contraception for the next seven days while continuing to take the other pills as normal. However, if you are breastfeeding a lot in the first six months and not having periods, you are likely to still be protected if you forget to take a pill.

If you vomit within three hours of taking a pill, take another pill. If you vomit again within three hours then you should follow the seven-day rule by using another form of contraception for the following seven days while taking the rest of the pills as normal.

Diarrhoea may also prevent the absorption of the mini pill. In this case use another form of contraception for seven days after the diarrhoea stops and continue to take the rest of the pill packet as normal.

Some medicines can make the mini pill less effective such as antibiotics and anti-epilepsy drugs. Ask your doctor about interactions with other medications you may be taking.


There is no increased risk of blood clots (thrombosis) or breast cancer from the mini pill.

The main risk is a slightly higher risk of ectopic pregnancy (when a pregnancy develops outside of the womb) if the pill fails.

Diabetics should be carefully monitored if they are taking the mini pill because the hormone progestogen can lower the body's tolerance of glucose.

The mini pill should not be taken by women with a history of breast cancer, liver problems, abnormal bleeding, or by those who suspect they are pregnant.

The mini pill is not associated with a risk of birth defects, but unnecessary drugs should not be taken while pregnant.

Side effects

The mini pill has fewer side effects than the combined pill. Any side effects which do occur will normally ease within three months of taking it. Side effects include:

Irregular periods

This is one of the most common unwanted side effects from taking the mini pill. There can be spotting between periods, your period may not be on time, and your period may also be lighter when taking the mini pill.

Some women do not have a period for several months while taking the mini pill. However, you should take a pregnancy test if you do not menstruate for more than 45 days.

Breast tenderness

Some women have breast tenderness on the mini pill, but this is a more common side effect when taking the combined pill.

Weight gain

This is a possibility with the mini pill, but again it is more common on the combined pill.


Some women experience nausea when they first start taking the mini pill. Some women find it helpful to take the pill after eating. Contact your doctor if nausea continues for more than a few months.


This is an uncommon side effect with the mini pill. Contact your doctor if you experience ongoing headaches or vision problems.

Ovarian cysts

There is an increased risk of ovarian cysts while taking the mini pill. Ovarian cysts occur when a follicle in the ovary continues to grow and becomes filled with fluid.

Other possible side effects include acne, excess body hair, depression and dizzy spells.

Getting help

See your doctor or local Family Planning clinic if you are interested in using the mini pill for contraception.

See also:

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