Menstrual symptoms are common, according to a national cross-sectional survey, but many young people receive little or no information about how to manage these. A total of 1334 individuals aged 13-25 years who had experienced ≥3 periods participated in an online survey between October 2021 and January 2022. Most reported regular dysmenorrhea (89%), fatigue/tiredness (78.1%), and mood changes (72.5%) associated with menstruation. Irregular cycles were reported by 53.5% of Māori compared with 41.7% of non-Māori. Most participants recognised the need to see a doctor for period pain that impacted their daily lives (84.7%), but were less likely to recognise noncyclical pelvic pain (45.7%), heavy bleeding (39%), and intermenstrual bleeding (29%) as symptoms that require a doctor’s visit. The main sources of menstrual health knowledge before menarche were a family member (74.2%) and health and physical education classes at school (63.7%). Many young people reported receiving little or no information about periods before menarche (37.9%), and very few received information on how to manage menstrual symptoms (15.1%).