Background: Menstrual problems during adolescence may affect emotional well-being, social participation, and school functioning. This study assessed short-term change in knowledge of psychosocial problems related to menstrual abnormalities after a planned school-based teaching program.

Materials and Methods: A pre-experimental one-group pretest–posttest study was conducted among 60 adolescent girls selected by purposive sampling from an English-medium high school in Bengaluru, India, during May 1–28, 2024. Knowledge was assessed with a structured 30-item questionnaire. The investigator delivered a 60-minute lecture-cum-discussion session each day for seven consecutive days. The posttest was administered on day 7. Paired score change was analyzed using a paired t-test with a 95% confidence interval (CI) and Cohen's dz. Secondary demographic associations were examined using exact tests.

Results: Mean knowledge score increased from 13.45 (SD 4.28) at pretest to 24.20 (SD 2.31) at posttest. The mean paired increase was 10.75 points (95% CI 9.64–11.86), t (59) =19.40, p<0.001, with Cohen's dz=2.50. At posttest, 44 participants (73.3%) had adequate knowledge, compared with none at baseline.