US Pharm. 2015;40(9):25-26.

Birth Control Pills

Oral contraceptives are drugs that are used to prevent pregnancy. Although no birth control method is 100% effective, oral contraceptives are generally 99.9% effective if they are taken according to directions. The primary action of these products is to prevent the release of an egg from a woman’s ovary (ovulation). Oral contraceptives are safe for most women, but they increase the risk of blood clots, stroke, pulmonary embolism, and heart attack, especially in women over 35 years of age who smoke. Oral contraceptives prevent pregnancy, but they do not prevent sexually transmitted diseases, such as HIV/AIDS.

The Pill Must Be Taken at the Same Time Each Day

In addition to being used to prevent pregnancy, oral contraceptives may be prescribed to treat some forms of acne. They also may be used to control abnormally heavy, painful, or irregular menstrual periods or premenstrual dysphoric disorder (also known as PMDD).

How Oral Contraceptives Work

Oral contraceptives work by several methods. For one, they contain hormones that prevent fertilization by blocking the release of an egg from an ovary each month. They also work by thickening the mucus in the cervix, which helps block sperm from reaching an egg. In addition, these hormones alter the lining of the uterus so that a fertilized egg cannot become attached and develop in the womb.

Types of Oral Contraceptives

Several forms of oral contraceptives are available, all of which require a doctor’s prescription. Most of these products contain estrogen and progestin components. There are also some combination products that contain an estrogen and drospirenone, a synthetic progesterone that is linked to an increased risk of serious side effects.

Oral contraceptives are usually taken for 21 days each month, followed by 7 days without the drug, during which time most women have withdrawal bleeding similar to a light period. The cycle is then repeated. Some products come in packs of 28 pills, with the last seven pills containing a lower dose of hormone, a vitamin supplement, or no active ingredient. Also available is an extended-cycle pill, which contains the same hormones but is taken every day for 12 weeks, followed by 1 week of either estrogen alone or no drug. This type of pill results in four menstrual periods per year. The minipill, another type of oral contraceptive, contains only progestin and is used by women who experience side effects from estrogen or who are breastfeeding. The minipill is slightly less effective than the combination product.

Usage and Side Effects

Oral contraceptives are packaged in special containers that make it easy to take them once a day. The pill should be taken about the same time each day. Many women take their pill with breakfast or dinner or at bedtime. It is very important to read the specific directions for taking the pills correctly. When first beginning oral contraceptives, be sure to follow your prescriber’s recommendation on how long to use another birth control method in order to be fully protected.

Common side effects of oral contraceptives include nausea, spotting between periods, weight gain, tender breasts, and changes in mood. Serious side effects are less likely, but should be reported to a doctor. These include swelling or aching legs or thighs, headache or blurred vision, chest pain, and abdominal pain. Women who have a history of blood clots, heart disease or high blood pressure, migraine headaches, or breast or uterine cancer should not use oral contraceptives.

Tell your doctor, pharmacist, and other healthcare professionals if you are taking oral contraceptives. The hormones in these pills can interact with many other drugs and herbal supplements, rendering either the oral contraceptive or the other medicine less effective. Be sure to ask your pharmacist if you have any questions about how to take the oral contraceptives prescribed for you.