Toktaş, İzzettinAkelma, HakanAraç, Eşref2023-12-252023-12-252023http://doi.org/10.1097/MD.0000000000036638https://hdl.handle.net/20.500.12514/5191Concerns about a possible relationship between vaccination against Coronavirus Disease 2019 (COVID-19) and menstrual disorders have been raised in the media. In addition, different studies have shown that the COVID-19 vaccine may be associated with menstrual changes. This study was conducted to investigate the effects of COVID-19 vaccines on the menstrual cycle in women. This cross-sectional descriptive study was conducted between August 16 and September 17, 2021. Data were collected through a self-administered questionnaire via an online form sent to the participants through social media. Data of 586 women were included in this study. A total of 82.4% (n = 483) of the participants were aged between 31 and 50 years. The BioNTech vaccine (2 doses) was administered to 75.8% (n = 444), Sinovac (3 doses) to 9.0% (n = 53) of the participants. 53.1% (n = 311) of the women experienced changes in their menstrual cycles. The most common menstrual changes after vaccination were delayed menstruation (n = 176; 30.0%) and prolonged menstrual duration (n = 132; 22.5%). Menstrual delay, prolonged menstrual duration, heavy bleeding, and early menstruation were more common in women than prior to receiving the vaccine (P < .05). More than half of the women experienced menstrual cycle changes after receiving the COVID-19 vaccine. Women experienced significantly higher rates of menstruation delay, prolonged menstrual duration, heavy bleeding, and early bleeding compared to before vaccination.en10.1097/MD.0000000000036638info:eu-repo/semantics/openAccessAdverse effectsCOVID-19 vaccinationMenstrual cycleMenstrual regularityMenstruation disordersArticle1025015Q3N/AWOS:0011270277000912-s2.0-8518008427338115291