An assessment of the side effects of switching from one oral contraceptive to another.

Side effects associated with three oral contraceptives were evaluated in a study in which women were switched to Norlestrin 1 from either Ovral (64 subjects) or Norinyl 1/50 (26 subjects). In the cycle prior to crossover, breast discomfort was more frequent among Norinyl users than among Ovral users. The prevalence of all other reported side effects was not significantly different for Norinyl and Ovral. The crossover to Norlestrin did not significantly change the numbers of patients reporting side effects. By the end of third Norlestrin cycle, rates of all side effects were similar for women who were switched from either Ovral or Norinyl.