Background <p>This study investigates the social impact of menstrual stigma in Spain. Whilst menstruation is a biological process, it is shaped by cultural norms that influence how it is perceived, experienced, and managed.</p> Methods <p>A nationwide cross-sectional mixed-methods survey was conducted with 4,028 participants aged 14 years and older. Quantitative items were analysed using descriptive statistics, while qualitative open-ended responses were thematically analysed through a constructivist lens to explore social perceptions, behavioural responses, and institutional dynamics related to menstruation.</p> Results <p>Menstruation affects participation in everyday activities, particularly those involving physical exposure such as sports, swimming, or wearing certain types of clothing. While some respondents reported avoiding activities due to physical symptoms, others cited anxiety, fear of leakage, or social discomfort, reflecting internalised stigma. In professional and educational settings, participants described presenteeism, reluctance to take leave, and a sense of pressure to minimise or conceal menstrual needs. Experiences of exclusion, whether from religious rituals, traditional roles, or interpersonal interactions, were also reported. Despite these challenges, the study highlights the positive role of supportive social environments. Solidarity, peer empathy, and institutional flexibility were identified as protective factors that help counter the effects of stigma. However, gaps in menstrual education and limited integration of menstrual health in clinical contexts continue to pose barriers to well-being and equity.</p> Conclusion <p>The findings underscore the need to recognise menstruation as a relevant factor in public health, education, and workplace inclusion. Addressing menstrual stigma requires structural attention and a shift from individual responsibility to collective and institutional support.</p>