Easy-to-read medicine information about the progestogen-only oral contraceptive pill – what is it, how to use it safely and possible side effects.
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What is the progestogen-only oral contraceptive pill?
The progestogen-only pill is form of contraception for women, to prevent pregnancy. It contains only one hormone, progesterone. It does not contain oestrogen.
- Easy to use – one tablet at the same time each day.
- It doesn’t interfere with sexual intercourse.
- Can be taken by women who are breastfeeding.
- There are very few side effects.
- If you are not good at remembering to taking a pill each day, then this is not right for you.
- The pill must be taken at the same time of the day whether you have sexual intercourse on that day or not.
- Some women can have irregular bleeding for a few months after starting the progestogen-only pill pill. So long as you have not missed any pills, it will still be working as a contraceptive.
- If the bleeding continues, talk with your nurse or doctor.
How does the progestogen-only pill work?
Some progestogen-only pills work mainly by thickening the mucus in the cervix so sperm can’t travel through it. Cerazette® also works by stopping a woman from producing a monthly egg, and changes the lining of the womb so it is less likely to accept a fertilised egg.
Who can take the progestogen-only pill?
This progestogen-only pill is especially recommended for women who are breastfeeding and women who cannot use the combined oral contraceptive pill for medical reasons such as having a history of:
- blood clots
- not being able to tolerate oestrogen.
The progestogen-only pill is not recommended for women who:
- have had breast cancer
- are taking some medications, over-the-counter preparations or herbal remedies — check with your doctor if you take regular medicine.
There are a few different brands of progestogen-only pill available in New Zealand, each containing a different progesterone. Your doctor will assess the best pill for you. If you experience side effects, you may need to try another brand, before you find one that is suitable for you.
How well does the progestogen-only pill work?
The progestogen-only pill is one of the more reliable forms of contraception.
- It is usually 92% effective, which means that in 92 out of 100 women, who use the progestogen-only pill each year, it prevents a pregnancy OR eight women out of 100 women who use the progestogen-only pill will get pregnant each year.
- If used perfectly (no pills are forgotten), the progestogen-only pill is 99% effective in preventing pregnancy.
- However, the effectiveness of the progestogen-only pill is highly depended on taking it correctly which means remembering to take it at about the same time everyday, whether you have sex on that day or not.
How to take the progestogen-only pill
You must take the progestogen-only pill every day with no breaks and no inactive pills.
- The usual dose of the progestogen-only pill is one tablet once a day.
- Some progestogen-only pills must be taken within three hours of the same time each day.
- Cerazette® must be taken within 12 hours of the same time every day.
- You can take the progestogen-only pill with or without food.
- You can start taking the progestogen-only pill at any time in your menstrual cycle.
- If you start on the first day of your period it is effective immediately.
- If you start at any other time during the menstrual cycle, the mucus effect will provide protection 48 hours later.
- To be completely safe you may want to use other contraception, such as condoms, or not have sex for 7 days after starting.
If you forget to take a progestogen-only pill, take it as soon as you remember.
- If you are more than three hours late in taking it (or more than 12 hours with Cerazette®) then your protection immediately fails.
- Continue taking your pill each day, but you will need to use extra contraception (such as condoms) for two days until the progestogen-only pill becomes effective again.
If you are unsure about what action to take if you have missed one or more pills, contact your doctor, nurse, pharmacist or call HealthLine 0800 611 116 for advice.
Diarrhoea and vomiting
Vomiting and persistent, severe diarrhoea can interfere with the effectiveness of the progestogen-only pill.
- If you vomit within two hours of taking your progestogen-only pill or have severe diarrhoea, the pill will not be absorbed.
- Carry on taking the progestogen-only pill as usual, but use other forms of contraception (such as condoms) for the duration of the illness plus for a further two days after the vomiting or diarrhoea has stopped.
If you are unsure about what action to take if you have vomiting and diarrhoea, contact your doctor, nurse, pharmacist or call HealthLine 0800 611 116 for advice.
Possible side effects
Like all medicines, the progestogen-only pill can cause unwanted side effects, although these are very rare and not everyone gets them.
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A number of medications and herbal supplements (e.g. St John's Wort) may interact with the progestogen-only pill and lessen its effectiveness, so always check with your doctor or pharmacist.
The following links provide further information about the progestogen-only pill:
Progestogen-only oral contraceptive pill NZ Family Planning
Progesterone-only contraceptive pill Ministry of Health, NZ
More detailed information on specific brands of the progestogen-only pill: