Women who suffer from severe menstrual pain could be allowed to take up to three days off work each month under a reform plan due to be approved by Spain's government next week.
Spain would be the first European country to do this, although there are several countries in Asia - including Japan, South Korea and Taiwan - that offer similar leave.
Previous studies estimate that 60% to 90% of young women worldwide suffer from dysmenorrhea - severe period pain - and in Spain, approximately 75% of women are affected, according to the International Journal of Environmental Research and Public Health.
The Secretary of State for Equality and against Gender Violence, Ángela Rodríguez, told El Periodico the new laws would benefit those suffering from particularly painful periods.
"It is important to clarify what a painful period is, we are not talking about a slight discomfort, but about serious symptoms such as diarrhoea, severe headaches, fever," said Ms Rodríguez.
The new laws, first revealed by the Cadena Ser radio station, also include other measures to improve menstrual health, including a requirement for schools to provide sanitary products for girls who need them.
Pads and tampons will also be provided free for marginalised women and will have the VAT removed from their sale in supermarkets.
Ms Rodríguez said: "The rights related to menstrual health have never been discussed and the data is chilling.
"One in four women cannot choose the feminine hygiene products she wants to buy for financial reasons. That is why we propose that they can be dispensed free of charge in educational and social centers."