What is the combined oral contraceptive pill?
The combined oral contraceptive pill (OCP), often just called 'the pill', prevents pregnancy. It can also help make periods lighter, less painful and more regular. Some doctors refer to it as the OCP.
How does the pill work?
The main way the pill works is by stopping a woman's ovaries from releasing an egg each month. It also thickens the mucus at the entrance of the uterus (womb), which prevents sperm from entering. And it changes the lining of the uterus, making it less likely the egg will implant.
Some types of the pill work from the first day they are taken, while others need to be taken for 7 days before they start working.
Types of combined oral contraceptive pills
There are many different types of combined OCP, but they all work in much the same way. If you are thinking about going on the pill, talk to your doctor about the best option for you.
The pill usually comes in a packet of 28, and you take one pill around the same time every day. With some types of the pill, you get 21 tablets after which you take a 7-day break and then start again. Check the instructions carefully.
Some types of the pill are available on the Pharmaceutical Benefits Scheme, which means they are cheaper to buy.
How well does the pill work?
The combined OCP works extremely well, provided you take it regularly and don't miss a dose. It might not work as well as it should if you don't take it regularly — even if you miss just one day. In real life, about 7 in every 100 women who take the pill for a year will still likely become pregnant.
What could go wrong?
Also, some medicines may prevent the pill from working, so you should ask your doctor or pharmacist about how any other medicines you need to take might affect it.
If any of these situations applies to you — including if you've missed taking your pill — you may be at risk of becoming pregnant and should consider using some other form of contraception (such as condoms) until you get your next period.
Advantages and disadvantages of the pill
Women can safely use the pill until they are 50. However, you should not take the pill if you have had a deep vein thrombosis, heart attack or stroke, a condition which increases the risk of blood clots, severe liver problems, some types of migraine, breast cancer or some types of lupus.
The main advantages of the pill are that it:
- is very effective if taken properly
- is safe for most women
- fertility returns as soon as you stop taking it
- can help regulate the menstrual cycle and reduce period pain
- can improve acne, endometriosis symptoms, pre-menstrual syndrome (PMS) and some symptoms of menopause
- probably decreases the risk of endometrial and ovarian cancers
The main disadvantages are that:
- it is not suitable for every woman
- it can cause side effects, especially when you first start taking it, such as:
- there is an increased risk of very rare blood clots or stroke
- it won't protect you from sexually transmitted infections (STIs); condoms are the only type of contraception that can do that
If you forget to take the pill
If you forget to take the pill, even once, you are probably no longer protected from pregnancy. Check the information on the packet for advice.
If you are not sure what to do, ask your doctor or call your local family planning association.
Resources and support
For more information, see Jean Hailes for Women's Health.
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Last reviewed: January 2021