If the combined oral contraceptive (COC) pill, simply known as birth control pill or the pill, is your preferred choice of birth control, and you are about to start taking it for the first time, you will need to know how to take it and what to do in certain situations (e.g. if you have missed one or more pills (discussed in another article), or you are taking medicines that might reduce its effectiveness). This is important in order to protect yourself from getting pregnant.
When to start using the birth control pill
The birth control pill should ideally be started on the 1st day of your period. However, it can still provide protection if started up to the 5th day of your period or menstrual cycle, without the need for you to use extra contraceptive protection such as a condom. If it is started at any other time in the cycle, additional precaution should be used for the first seven days.
Before you start using a birth control pill, you should also be certain that you are not pregnant. If you are not sure, then a high-sensitivity urine pregnancy test (HSUPT) should be done in order to confirm that you are not pregnant, before starting on the pill.
If you have infrequent or irregular menstrual bleeds, it is advisable to start the pill after being certain that you are not pregnant or carrying out an HSUPT (if necessary). You may also require additional contraceptive precaution for the first 7 days.
Starting birth control pill after childbirth
If you are thinking of starting the pill after the birth of your baby, your start date would depend on whether you are breastfeeding or not.
If you are breastfeeding, it is best to wait at least 6 weeks before starting on the pill. You will require an initial doctor consultation to assess whether it is safe for you, and you may discuss with the doctor alternative contraception to be used during the 6 weeks.
If you are not breastfeeding, you can start the pill after 3 weeks following childbirth, provided you have no added risk factors for venous thromboembolism (VTE) (e.g. postnatal immobility or a complicated pregnancy or birth). If you have additional risk factors for VTE, it is best to wait for 6 weeks before starting on the birth control pill (after discussing with the doctor to ensure it is safe for you).
If you are starting the pill after emergency contraception or switching from another method of contraception, the advice would be different (look out for the article on switching from other contraception methods to birth control pills).
How to take the birth control pill
The birth control pill must be taken orally, one pill each day, before or after food. It is important to take the pill every day, and around the same time each day. It is better to choose a time of day, or an activity you do everyday, to help you remember when your pill is due. You can also set reminders on your mobile phone to alert you of the timing of your pill.
If you take the pill more than 24 hours after it is due, then that pill is counted as a missed pill (see article on how to manage missed pills).
Using birth control brands with 21 pills per pack
These birth control pills contain 21 active/ hormone pills. Some brands also provide additional 7 inactive/ hormone-free/ placebo pills.
As discussed earlier, the pill is best started on the first day (or within the first 5 days) of your next period, as this provides most contraceptive protection. If you start the pill on any other day, you will need to use additional protection (such as a condom) for the first 7 days. Once started, you should take one pill at about the same time each day.
After taking the 21 pills, you will have a pill-free break for 7 days (or a hormone-free break for 7 days if your pack contains the 7 inactive/ hormone-free/ placebo pills). During the 7-day pill-free or hormone-free break, you may have some bleeding. This is called withdrawal bleeding and it is like a period. You will be protected from pregnancy during this time, provided you have been taking your pills correctly without miss and you start the next pack on time.
You must start the next pack after the 7-day pill-free or hormone-free break, regardless of whether you have the bleeding or not, or whether the bleeding has stopped or not. If you take the pill correctly, you will start the first pill of each pack on the same day of the week.
Using birth control brands with 28 pills per pack
These brands contain 24 active/ hormone pills and 4 inactive/ hormone-free/ placebo pills, 28 pills in total. Just like the 21-day pills, these pills are best started on the first day (or within the first 5 days) of your next period, as this provides most contraceptive protection. If you start on any other day, you will need to use additional protection, such as a condom, for the first 7 days. Once started, you should take one pill at about the same time each day.
After taking the 24 active/ hormone pills, you will have 4 inactive/ hormone-free/ placebo pills. During this 4-day hormone-free break, you may have some withdrawal bleeding that resembles your period. You will be protected from pregnancy during this time, provided you have taken your pills correctly without miss and you start the next pack on time.
As soon as you finish one pack of 28 pills, start the next pack on the following day, regardless of whether you have the bleeding or not, or whether the bleeding has stopped or not. With 28-day pills, you don't have to remember to restart the pill after a 7-day break and can easily develop a routine of taking a pill every day.
Taking other medications or supplements while using the pill
There are some medicines and over-the-counter products that can influence the contraceptive effect of the birth control pill.
Enzyme inducers is a particular category of prescribed medicines that can reduce the effectiveness of the pill. Some examples of these medicines include those that are used to treat epilepsy, tuberculosis (TB), HIV and St John's wort (a commonly used herbal remedy).
The birth control pill can also affect the blood levels of certain medicines. A particular one being lamotrigine, which is taken for epilepsy. In such cases, a birth control pill may not be the right method of contraception.
It is always best to let the doctor know about all the medicines you are taking, including those purchased over-the-counter, before starting the birth control pill. When buying any new medication over-the-counter, ask the pharmacist whether there are any possible interactions with birth control pills, before purchasing. Or talk to the doctor about any other medication or supplement you are required to take while already using the birth control pill. If the effectiveness of the pill is significantly affected by a medicine or supplement that you are required to take, then you may need to consider alternative forms of contraception.
Another important thing to bear in mind is that if you are required to take medicines with potential harm to the fetus in case of a pregnancy, it is advisable to consider long-term methods of contraception to reduce the risk of an unplanned pregnancy.
In the past, it was recommended that if you were taking antibiotics and were also taking the pill, you should use additional contraception such as a condom. This is no longer the current recommendation after more recent evidence was reviewed. Antibiotics therefore do not interfere with the effectiveness of the pill. You should continue taking your pill as normal if you also need to take any antibiotics. The exception to this would be antibiotics that are also enzyme inducers as well as those causing vomiting or severe diarrhoea.
Other circumstances that affect pill-taking
If you vomit within 2-3 hours of taking a pill, the pill will not have been absorbed. This may be considered as a missed pill and you will have to follow the appropriate advice (see article on managing missed pills). If you are not sure you can get advice from one of our doctors on what to do in such situations. Mild diarrhea does not affect the absorption of the pill. However, if you have severe diarrhea that may affect absorption, then the pill you have taken may be counted as a missed pill.
London A, Jensen JT. Rationale for eliminating the hormone-free interval in modern oral contraceptives. Int J Gynaecol Obstet 2016;134:8–12.