More than half (52%) of women in the UK said they felt pressure to go to work even when having severe period pain, according to data from Endometriosis UK.
A quarter (24%) reported having problems at work because of time taken off for pain.
Only 29% of women who had severe period pain went to a doctor or healthcare professional.
Among those who did not seek help, nearly a quarter (23%) said they did not think they would be taken seriously, and 51% thought painful periods were just a normal part of life.
Among 18 to 24 year olds, 62% said they knew what endometriosis is, but 27% had never heard of it.
Across all those surveyed, 80% had heard of endometriosis and 74% could correctly say what the condition is.
Most (62%) said they had missed out on sport or exercise because of period pain.
Emma Cox, CEO of Endometriosis UK, said: “Workplaces must be sensitive to the needs of employees experiencing severe period pain.
“We have to normalise conversations around period and pelvic pain in workplaces, and provide effective menstrual health education in schools, to support future generations.
“We want all UK governments to commit to bringing down the unacceptable waiting times for endometriosis diagnosis, and all other menstrual health conditions.”
Cox added: “Anyone with a menstrual health condition must feel confident that their concerns will be taken seriously when they speak to a medical professional.”