Spain's cabinet has approved a bill that grants paid medical leave for women who suffer from severe period pain, becoming the first European country to advance such legislation.
Menstrual leave is currently offered only in a small number of countries across the globe, among them South Korea and Indonesia.
But the proposed legislation must still be approved by the Spanish parliament, with a vote not expected for months.
It was not clear whether Socialist Prime Minister Pedro Sanchez's minority coalition government, which has made women's rights a priority, has enough support in the assembly to pass it.
The Spanish bill entitles workers experiencing period pain to as much time off as they need, with the state social security system - not employers - picking up the tab for the sick leave.
As with paid leave for other health reasons, a doctor must approve the temporary medical incapacity.
Equality Minister Irene Montero said the law will recognise a health problem that has been largely swept under the carpet until now.
"Periods will no longer be taboo," she told a news conference after the cabinet approved the bill.
"We will be the first country in Europe to introduce a temporary sick leave that is fully financed by the state for painful and incapacitating periods," she added.
"No more going to work with pain, no more taking pills before arriving at work and having to hide the fact we're in pain that makes us unable to work."
Ms Montero belongs to the far-left Podemos party, Mr Sanchez's junior coalition partner which has been the driving force behind the law.
About a third of women who menstruate suffer from severe pain, according to the Spanish Gynaecology and Obstetrics Society.
In 2016, Italy proposed a bill that would have granted three paid days off to women suffering menstrual pain who obtained medical certificates.
But the draft bill did not progress before the parliamentary term expired in 2018.
Spain's proposal has divided politicians and even unions, with some saying it could stigmatise women in the workplace and favour the recruitment of men.
"You have to be careful with this type of decision," said Cristina Antonanzas, deputy secretary general of one of Spain's largest trade unions, the UGT, warning it could impact "women's access to the labour market".
But Spain's other major trade union, the CCOO, said the proposed measure was "justified" if period pain prevents a woman from working, and called it a major "legislative advance".