Oral Contraceptives

Oral contraceptive pills have been available since the 1960’s as a way for women to prevent pregnancy and have control of their fertility. They were the first type of medicine to be approved for long-term use by healthy people and the first 99% effective way to prevent pregnancy. They are now one of the most widely used medicines in the world.

Oral contraceptives are prescription medicines and you need to visit your medical centre or Family Planning Clinic for a prescription. However, since 2017, pharmacists who have undertaken specific training are now able to supply some brands of oral contraceptive, without the need for an appointment. As long as you have previously been prescribed an oral contraceptive within the last three years, you may be able to get a prescription from your local pharmacy if you have run out of your pill or want to restart it.

There are two main types of oral contraceptive pill – combined oral contraceptives (COCs, “the pill”) and progesterone-only pills (POPs, “the mini-pill”). They differ in the types and amounts of hormones they contain, how they work to prevent pregnancy and their side-effects. This has advantages as it means that if one type of oral contraceptive causes side effects that bother you, or you can’t take it because of medical conditions you have, then another oral contraceptive might be better for you.

Combined oral contraceptives (COCs) contain two hormones, oestrogen and progesterone. They prevent pregnancy by stopping an egg being produced (ovulation), thickening the cervical mucus and altering the uterus lining so that if an egg was fertilized, implantation would be much harder. Not everyone can take these medicines. Smokers, women who are overweight, migraine sufferers, women with high blood pressure or liver disease as well as anyone with a family history of blood clots cannot take a COC. Women taking certain medicines such as St John’s Wort or anti-epileptics cannot take COCs either. COCs cause side effects such as nausea, headaches, skin breakouts, mood changes and breast tenderness.

Most COC brands contain packs of 28 pills to be taken every day. The first 21 pills are ‘active’ containing oestrogen and progesterone, and the last 7 tablets of the pack are ‘inactive’ with no hormones (called sugar pills). During the 7 days of inactive pills you have bleeding like a normal period.

COCs are only 99% effective if they are taken every day. There are special rules that you need to follow if you miss a pill. The rules are different depending where you were up to in the pack when you missed your pill.

Progesterone-only pills (POPs) contain only one hormone, progesterone and are slightly less effective than COCs at preventing pregnancy (96-99%). Some POPs prevent ovulation but most thicken the cervical mucus so that sperm cannot reach the uterus. They are the best option if you can’t tolerate oestrogen, suffer from migraines, or have a history of blood clots. They are safer for use in older women, and also if you are breastfeeding.

You need to take the POP every day but there are no breaks or inactive pills. An important thing to remember when taking a POP is that it must be taken at about the same time every day (within 3 hours) or it won’t be effective. POPs have less side effects, causing irregular or no periods (many women find this an advantage) and they can increase the risk of ovarian cysts.

If you are taking either type of oral contraceptive it is very important to be aware that they can be ineffective at preventing pregnancy if you have vomited within two hours of taking a pill or had a bout of diarrhoea. It is always worth talking to a health professional if you have been sick and are worried this may have affected the pill. They can also give you advice about what to do if you have missed pills and if there is a need to take the emergency contraceptive pill.

This blog provides general information and discussion about medicine, health and related subjects. The information contained in the blog and in any linked mate­ri­als, are not intended nor implied to be a substitute for professional medical advice.