The oral contraceptive pill (the Pill) is a combination of two female sex hormones that prevents pregnancy by changing the hormone balance in your body to stop ovulation (the monthly release of the egg from the ovary). If taken according to instructions, it is at least 98 to 99 percent effective.
To be effective to stop pregnancy, the Pill must be taken at a regular time. Periods tend to become shorter, regular and lighter. The Pill also tends to stop painful periods. The Pill can interfere with the quantity and quality of breast milk, so it is better to use other contraception during breastfeeding. Antibiotics, Vitamin C, vomiting and diarrhoea may affect the pill and therefore extra protection is necessary whilst continuing to take the Pill and for seven days after. The most common side effects are nausea (feeling sick), breast tenderness and breakthrough spotting. These side effects often disappear after a couple of months on the Pill. Not all women can take the Pill. Women who have blood-clotting tendencies, hormone-dependent tumours (such as breast cancer), high blood pressure and diabetes or are heavy smokers (especially over the age of 35) should consider alternative methods.