Oral contraceptive pill
There are many different types of oral contraceptive pill (also known as birth control pills or ‘the pill’). They either contain a combination of the hormones progesterone and oestrogen (combined oral contraceptive pill) or they may contain progesterone only (the mini pill). They work by preventing the release of eggs from the ovaries and/or thickening the cervical mucus to prevent sperm from entering the uterus.
For oral contraceptive pills to be effective, you must take them on the same time every day and you must not miss taking any tablets.
- Advantages: can reduce some premenstrual syndrome (PMS) symptoms and bleeding irregularities, can improve acne
- Disadvantages: the effectiveness may be reduced when taking certain antibiotics or if diarrhoea/vomiting occurs, no protection against STIs, rare but serious side effects such as increased risk of blood clots especially in smokers and women over 35-years-old
The contraceptive patch is a small square of adhesive that contains a combination of the hormones progesterone and oestrogen which are absorbed through your skin into your bloodstream. The hormones work in the same way as the oral contraceptive pill by preventing the release of eggs from the ovaries and by thickening the cervical mucus to prevent sperm from entering the uterus.
The patch is applied to areas of clean dry skin on your upper arm, upper torso, abdomen or buttocks once weekly for three weeks out of every four. It can be worn when swimming, in the shower or during exercise.
- Advantages: convenient weekly administration, easily removed if you want fertility to return, easy to use for people who have difficulty swallowing tablets
- Disadvantages: rare but serious side effects such as increased risk of blood clots especially in smokers and women over 35-years-old, no protection against STIs
The contraceptive injection, also known as DMPA or DepoProvera, contains the hormone depot medroxyprogesterone acetate (a type of progesterone). It is given by intramuscular injection into the upper arm or buttocks every three months (four times a year). It works by preventing the release of eggs from the ovaries and by thickening the cervical mucus to prevent sperm from entering the uterus.
- Advantages: convenient, long acting for up to three months
- Disadvantages: may cause weight gain and irregular bleeding in some people, does not provide protection against STIs, may affect bone density with long term use, should not be used for longer than two years