How birth control pills work
The combined pill contains synthetic versions of the female hormones oestrogen and progesterone. The hormones affect your ovulation and menstrual cycle. When you take the pill correctly, it’s over 99% effective at preventing pregnancy.
How do birth control pills prevent pregnancy?
Stopping the sperm from reaching the egg – the cervical fluid becomes thicker, making it more difficult for sperm to get into the uterus
Stopping the release of an egg – ovulation stops so that the sperm and egg never come into contact
Stopping the implantation of the egg – the lining of the uterus thins out so that a fertilised egg can’t stick to it
The pill can be prescribed by a doctor and other healthcare professionals for free.
How to take birth control pills
Starting on the first day of your period
If you start taking your birth control pills on the first day of your period, you’ll be protected against pregnancy right away.
Starting any other day of your menstrual cycle
If you take your first pill any other day in your menstrual cycle, you need to use an additional form of contraception for 1 week before your birth control pills provide full protection.
You need to take your pills at about the same time each day. If you don’t do this, you’re at risk of getting pregnant and you should use another contraceptive. To help yourself remember, take the pill at the same time you do another daily routine, like brushing your teeth.
The pill comes in a small pack with either 21 or 28 pills.
Packs with 21 pills
If you have a pack of 21 pills, take one pill every day and then take a break for 7 days before starting a new pack.
Packs with 28 pills
A pack of 28 pills contain 21 pills with hormones and 7 sugar pills that don’t contain any hormones at all. Take one pill every day – you don’t have to keep track of when to stop and when to start a new pack.
When do you get your ‘period’ on birth control pills?
During the 7 days when you’re taking sugar pills or not taking any pills, you may get withdrawal bleeding. It may feel like a period, but it’s not actually menstrual bleeding.
How do you skip your ‘period’ on birth control pills?
If you want to avoid withdrawal bleeding, start your next pack of birth control pills immediately after you finish your last one without taking a week off or taking sugar pills. . After 3 to 4 months of back-to-back use, you may get some breakthrough bleeding.
How effective are birth control pills?
The pill is very effective at preventing pregnancy, but only if you always take your pills regularly, every day at about the same time. Keep in mind that birth control pills don’t protect against sexually transmitted diseases and infections – only condoms do.
What to do if you miss a birth control pill
If you’ve missed 1 pill
If you accidentally forget to take a pill, take it as soon as you remember, even if that means taking 2 pills in the same day. If it’s been less than 36 hours between pills, you’ll still be protected from pregnancy.
If you’ve missed 2 pills
If it’s been over 48 hours since you’ve taken a pill, you may not be protected against pregnancy. You should take the last pill you missed, even if that means taking 2 pills in one day. You should use another form of contraception, like a condom for the next 7 days.
If you’re sick
If you vomit or have diarrhoea within 4 hours of taking a pill, your body most likely didn’t have enough time to absorb it and you’ll need to take another pill.
If you’ve had sex without being fully protected, there are emergency contraception methods to prevent pregnancy, including the morning after pill or copper IUD.
What are the side effects of the birth control pill?
The hormones in the pill can affect the body in different ways. Some people don’t have any problems at all, while others may experience some side effects. For example, you may have intermittent bleeding, decreased sex drive or feel depressed when taking the pill. The side effects usually disappear after a few months, but they can also last for longer.
Common side effects of birth control pills:
Sensitive or swollen breasts
Breakthrough bleeding or spotting
If you’re not happy with your birth control pill, you can try a different kind of pill or choose an entirely different method of contraception.
The progestogen only pill (POP), or mini pill, is an oral contraceptive without synthetic oestrogen. They may have fewer side effects than combined birth control pill.
You might also want to give other contraceptive methods a try. There are several other hormonal contraceptive methods, like the implant or hormonal IUS. You could also opt for a non-hormonal method.
Risk factors associated with the birth control pill
The synthetic version of the sex hormone oestrogen in the pill can increase your risk of blood clots. The risk is small, but you shouldn’t take the pill if you’ve been treated for blood clots or have a predisposition to them.
Smokers, people over 35 and people with underlying medical conditions might be advised to avoid the pill and instead opt for a different contraceptive. If you need advice, talk to a healthcare professional before starting the pill.
Advantages of birth control pills
If you experience period pain, heavy menstrual bleeding, premenstrual problems such as premenstrual syndrome (PMS) or premenstrual dysphoric disorder (PMDD), birth control pills can help relieve your symptoms. You’ll also likely get regular, lighter bleeding and since your ovulation will be stopped, you may get relief from any pain you might have during ovulation.
The pill is also a common treatment for polycystic ovary syndrome (PCOS), to treat hormonal imbalances in the body. Acne can also be treated with birth control pills. Taking the pill may also reduce the risk of ovarian, uterine and bowel cancers.
How to stop taking birth control pills
You can stop taking birth control pills at any time. If you stop mid-pack, you might get irregular bleeding, so you might want to wait until you finish an entire pack to avoid this.
You can get pregnant if you’ve had vaginal sex during the last few days before you stop taking the pill. Use another form of protection if you want to avoid pregnancy.
You’ll start menstruating and ovulating again once you stop taking the pill. For some people this happens right away, and for others it takes a few months before the body gets back to its usual rhythm.
When you should seek medical attention
If you’re taking the pill and feel unwell physically or mentally, contact a healthcare provider. You may wish to switch to a different type of pill or choose a different method of contraception.
If you’re getting heavy or prolonged bleeding while taking the pill, talk to a healthcare professional.
Seek urgent medical attention if you have chest pain, severe stomach pain, severe headaches or blurred vision. If you have swelling or aches in your legs or thighs, you should also get medical attention immediately.
- Reviewed by:
Dr Roshaan Saloojee
- Last updated: