The progesterone only pill (sometimes called the mini pill) is a daily contraceptive containing one hormone: progestogen. Depending on the type of progesterone only pill , it works by preventing ovulation (the release of an egg), thickening cervical mucus to stop sperm reaching an egg and changing the lining of the womb, making it less suitable for pregnancy.

This pill must be taken every day, with no break between packs. Often these pill need to be taken around the same time each day to be effective and this is an important consideration when deciding if this is the right pill for you.

The progesterone only pill can be a suitable option for many, including those who cannot take oestrogen.

It is an effective contraception when taken correctly. It can be used while breastfeeding and is also an option for people who smoke, including those over 35 (following a suitability assessment).

It is reversible, meaning fertility usually returns shortly after stopping.

Unlike the combined pill, the progesterone only pill does not contain oestrogen, so it does not carry the same increased risk of blood clots associated with combined hormonal contraception. However, the progesterone only pill may not be suitable for you if you have any of the following:

• Current or previous breast cancer.

• Certain liver conditions.

• Unexplained vaginal bleeding.

• Medicines that can affect how well the pill works, such as some treatments for epilepsy, tuberculosis, HIV or the herbal remedy St John’s Wort.

Because the progesterone only pill needs to be taken at roughly the same time every day then you need to ensure that you can stick to such a schedule for the contraception to be effective.

As with all medication, there is a risk of some side effects when starting the progesterone only pill. These side effects vary from person to person and often settle over time as your body gets used to the medication.

Potential side effects can include:

• Changes to your periods, including irregular bleeding, spotting, lighter periods or no periods.

• Breast tenderness.

• Headaches.

• Acne.

• Mood changes.

• Changes in libido (sex drive).

• Feeling sick (nausea).

If you have unusual bleeding, severe abdominal pain, or symptoms that concern you, speak to a healthcare professional.

For many people, yes. The progesterone-only pill can be a suitable option if you cannot take oestrogen, although we will discuss this with you during our online consultation so you have all the information you need to decide if this is the right pill for you.

It can. Some people experience lighter periods, irregular bleeding or no periods at all. Changes to your bleeding pattern are common, especially during the first few months.