Oral contraceptives (OCs) are the most common form of reversible birth control and are used by about 80 percent of women in the United States at some time during their reproductive lives. OCs also are widely prescribed for the treatment of menorrhagia or dysmenorrhea, even though the long-term success of this management is unknown. Side effects are widely believed to influence compliance with treatment, but the incidence of side effects in women beginning new low-dose therapy with OCs is unknown. The most common side effects are nausea and vomiting, breakthrough bleeding and spotting, headaches, bloating or swelling, and breast tenderness. Sulak and colleagues prospectively studied symptoms in women currently using or starting treatment with OCs to assess the type, frequency and duration of side effects during the 21 days of therapy with active pills compared with the seven days of therapy with hormone-free pills.

Women who had never used OCs, had used OCs but not in the previous three months or had been using OCs for at least 12 months were eligible for the study. Twenty-one combination pills containing 35 μg or less of ethinyl estradiol plus a progestin and seven hormone-free pills were given to each patient. For at least two full cycles, established users were asked to keep a daily symptom diary recording common side effects and analgesic use. New users recorded this information for three cycles. Menstrual blood flow was graded on a four-point scale, while side effects, such as pelvic pain, cramps and headaches, were recorded on a 10-point scale. Demographic information, including age, weight, height, education, race and gravidity, was recorded.

Most of the patients included in the analysis were white (84 percent) and had at least a high school education (97 percent). Symptoms were more common during hormone-free days than during the other part of the cycle when patients were taking hormones. These differences were statistically significant for pelvic pain, headaches, bloating or swelling, and breast tenderness in new and established users. Use of analgesics also was significantly increased during hormone-free periods. Symptoms gradually decreased in new users and by the third cycle, their symptom patterns were similar to those of established users.

The authors conclude that significant symptoms develop during the hormone-free phase of OC use and suggest that current regimens be manipulated to reduce this symptom burden. Options include increasing duration (up to 12 weeks) of the hormone phase, followed by one week of withdrawal from estrogen and progestins. Other options include reducing the number of hormone-free days (to five or less per month) by increasing the number of days of combined hormone intake or by adding estrogen on additional days to leave only two hormone-free days per month.