Patient-reported outcomes after switching from brand-name to generic drospirenone/ethinylestradiol combined oral contraceptives: a questionnaire-based observational study

Background In Japan, the term “low-dose estrogen–progestin (LEP)” refers to combined oral contraceptive (COC) formulations that are pharmacologically equivalent to COCs but are primarily approved for therapeutic indications rather than contraception. Although bioequivalence between brand-name and generic formulations is required, patients sometimes report subjective differences after switching. This study aimed to evaluate patient-reported outcomes after switching from brand-name to generic drospirenone/ethinylestradiol LEP/COC formulations. Methods This questionnaire-based observational study included women who switched from a brand-name to a generic drospirenone–ethinylestradiol LEP/COC formulation between October 2022 and July 2023 and completed at least three cycles of the generic product. Six subjective symptoms—gastrointestinal symptoms, nausea/vomiting, irregular bleeding, dysmenorrhea, premenstrual syndrome, and headache—were assessed as improved, worsened, or unchanged. Free-text comments and one-year continuation outcomes were also analyzed. Results Eighty-one women were included. Overall, 26 patients (32%) reported some difference after switching, whereas the majority reported no change. “No change” responses were significantly predominant for all symptoms (p < 0.01). Among patients who perceived changes, headache was the only symptom significantly more likely to worsen than improve (p = 0.03). Four patients (5%) reverted to the brand-name formulation, all reporting symptom worsening and additional negative impressions in free-text responses. Conclusions Most patients did not perceive clinically meaningful differences after switching from brand-name to generic drospirenone/ethinylestradiol LEP/COC formulations, supporting their overall interchangeability. Perceived differences appear to be influenced largely by psychological factors rather than pharmacologic differences. Appropriate counseling and reassurance are essential when switching to generic formulations.