Girls at Oxford Spires Academy were sent an email from the head of sixth form and vice principal, Dr Jackie Watson, who said: "Learning to deal with monthly inconvenience is all part of being a woman".
The message was sent to all Year 12 students - including the male pupils - and has been hit with serious backlash from students and parents.
In the email, Dr Watson said: "Any female student asking to be sent home 'ill' or phoning in 'ill' who has a period will not find this is a suitable excuse.
"Learning to deal with monthly inconvenience is all part of being a woman, I'm afraid."
One student commented: "Obviously I have to understand that people cannot take their whole period off each month but that is not what anyone is trying to do.
"Personally, when I am on my period, I experience really painful cramps, meaning I cannot walk without having to be bent double.
"Sometimes, I get so dizzy I pass out or vomit - obviously on these days, I would not consider myself fit to go into school.
"The fact Dr Watson sent the email out to the whole of sixth form as well, including the boys, is just making boys think it isn't bad and that they shouldn't be sympathetic.
"I am now quite uncomfortable to think of my next periods and how I will manage them at school, as I'm sure the majority of girls are."
Another student added: "Obviously as women, we must find ways of dealing with this, but occasionally, the pain is too much to handle.
"We understand the motive behind the email, and we don't want to use our periods as a way to prevent our learning but we feel there is a lack of compassion for what girls experience each month."
Dr Watson has since commented on her email, explaining it was not intended to address the worst case scenarios.
She said: "Anywhere where you work you can't take two days off for being on your period.
"If it's just an ordinary period, you should come into school - unfortunately taking that time off is not how society works.
"The email is about attendance, that was simply the point - my slightly tongue-in-cheek way of saying it maybe got to some of the girls, but the email was to get across the message to be in school.
"I do think they're right to be upset about that [the email being sent to boys] and I probably shouldn't have done that and perhaps it was a bit foolish of me."
Dr Watson also added that the school spends "a huge amount of time supporting students with issues and health-related matters".
Oxford locals were not impressed with the email, however.
One said: "It's particularly sad when a professional woman demonstrates a lack of empathy for young women who experience especially heavy bleeding or pain.
"For girls who experience flooding in the first few days, bleeding through their clothes, despite 'doubling up' with a tampon and towel together, is mortifying, especially in a mixed school.
"I'm afraid this teacher's email is ill considered and totally devoid of empathy for the minority of girls who need to take time off. She's clearly one if the lucky ones."
Meanwhile one mum said: "My daughter used to vomit, pass out and have seizures. Some months she couldn't even stand up for two or three days.
"Not everyone is the same! I am sure there are other ways of managing attendance numbers!"
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