The Pill - Combined | Progesterone Only
There are two types of contraceptive pill. The Combined Pill contains two hormones similar to those produced naturally by the body; progestogen and oestrogen. The Progestogen Only Pill, also known as the “mini pill” contains only progestogen.

Quick Guide
Key Facts about the Pill
Combined Pill
Progesterone Only Pill
Pros & cons
- The pill is up to 99% effective when taken correctly.
- It doesn’t interrupt sex.
- There is no evidence that it causes additional weight gain.
- It does not protect you from STIs.
- There can be temporary side effects from the pill.
- You will need to take a pill every day.
- You will need to see a nurse or doctor for check ups and a prescription.
- See the pros and cons tab for more detail on each pill option.
Where to get it
The pill needs to be given by a doctor, midwife or nurse who has been specially trained. There may be a cost for the appointment and prescription. Please check with your doctor, midwife or nurse. Click here to find your nearest service.
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How It Works
Combined Pill
The combined pill works to prevent the sperm reaching the egg and fertilising it. It prevents pregnancy by interrupting this process in three ways:
- It stops eggs being released from the ovaries (ovulation).
- It makes it harder for the sperm to reach the egg.
- It makes the uterus (or womb) lining thinner so a fertilised egg cannot implant.
Progesterone Only Pill
The POP pill works by preventing the sperm reaching an egg and fertilising it. It interrupts the process in two ways:
- Thickening the mucus from your cervix, making it difficult for sperm to move through and reach an egg.
- It sometimes stops your ovaries releasing an egg (ovulation). This is the main action of POPs containing the hormone desogestrel.
Pros & Cons
Combined Pill
Pros
- It is over 99% effective if taken correctly.
- It doesn’t interrupt sex.
- There is no evidence that it causes additional weight gain.
- There are no long term effects to your fertility.
- It can help make your periods lighter, more regular, and reduce period pains.
- It may also help to reduce premenstrual symptoms (PMS).
- Certain brands can improve acne.
- The pill can also have additional health benefits, such as reducing the risk of cancer of the ovaries, womb and colon.
Cons
- Temporary side effects during the first few months, like headaches, nausea, breast tenderness and mood swings.
- It can increase your blood pressure.
- It does not protect you from STIs.
- Breakthrough bleeding and spotting (this means bleeding outside of the seven day break) is common when you first start taking it.
- Vomiting, diarrhoea and other medications can affect how the combined pill works.
- You will need to see a nurse or doctor for check ups and prescriptions.
Progesterone-Only Pill
Pros
- It is over 99% effective if taken correctly.
- It doesn’t interrupt sex.
- There is no evidence that it causes additional weight gain.
- There are no long term effects to your fertility.
- It can be taken by some women who cannot use contraception that contains oestrogen, such as the combined pill, contraceptive patch or the vaginal ring.
Cons
- Your periods may become irregular. They may happen more often, less often, be lighter or stop altogether. You may also get spotting in between periods.
- It doesn’t protect against STIs, so you will need to use a barrier method such as condoms.
- You have to take the progesterone only pill around the same time every day (within three hours for some progesterone only pills, and 12 for those containing desogestrel).
- Some medicines and certain types of antibiotic can make the progesterone only pill less effective.
- You may get some side effects when you first start taking the progesterone only pill, such as spots, headaches, weight change and breast tenderness. These should stop within a few months.
- Vomiting and diarrhoea and can affect how the progesterone only pill works.
- You will need to see a nurse or doctor for check ups and prescriptions.
FAQs
Where to get the pill?
The pill needs to be given by a nurse, midwife or doctor who has been specially trained. Visit your local doctor or nurse or speak with your midwife to find out more. There may be a charge for your appointment and the prescription, so make sure to ask when you get in touch.
How to take the pill?
There is now new guidelines (2019) that confirm it is safe to take the combined pill continuously without a seven day break – take the 21 hormone pills, then start a new packet straight away. This means missing the non-hormone pills and skipping your period. This is the most effective way to take the combined pill.
The progesterone only pill should be taken every day with no break in between packs.
For all pills:
- Choose the time of day that suits you best.
- Take it at the same time every day until you finish the packet (this is helpful for remembering and getting into the habit of taking it).
- Always follow the instructions that come with the packet, paying careful attention to which medicines and antibiotics might affect it.
When will I be protected from pregnancy with the pill?
If you start taking the pill in the first five days of your period, you will be protected against pregnancy straight away. If you have a short menstrual cycle, where your period is normally 23 days or less, you will need to start taking the pill in the first four days to be immediately protected (because you might ovulate early).
If you are taking the combined pill – if you start the pill at any other time in your menstrual cycle you will need to use additional contraception, such as condoms, for the first seven pill taking days.
If you are taking the progesterone only pill – if you have a short menstrual cycle, where your period is normally 23 days or less, starting on the fifth day of your period may mean you are not immediately protected (because you might ovulate early). You therefore may need to use additional contraception, such as condoms, for the first two days. If you start taking the pill at any other time in your menstrual cycle, it will take two days before it starts to work. So you’ll need to use condoms for the first two days.
Make sure you read the instructions for the pill prescribed to you and as directed by your doctor, midwife or nurse.
What happens at an appointment?
An appointment will typically include:
- A few questions about your medical and family history, to work out what would suit you best.
- The doctor, midwife or nurse will take your blood pressure and they will weigh you.
- You’ll discuss other medicines you are taking in case they make the pill less effective.
- When you first start the pill you will usually be given a three month supply. Follow up appointments and reviews are then usually every 6-12 months providing there are no issues. You can return to your nurse or doctor at any time if you are worried about anything.
I’ve been taking the pill for years is it safe?
The short answer is yes—there’s no reason to take a break from the pill unless you’ve decided you want to get pregnant.
There’s been lots of research on contraception pills over the years and the consensus is that long-term use doesn’t affect your ability to get pregnant once you stop taking the pill. It’s always a good idea to stay current on your annual health exams, whether you use the pill or another method. Our health changes over time, and some changes like rising blood pressure or worse migraines may make it risky to use methods with estrogen.
Page last updated: 23 January 2020. Reviewed for clinical accuracy.