Young women are regularly bedridden by period pain, a survey has shown.
An estimated 60% of women visit their GP because of period pains
It found 10% had had to take time off work each month, leading them to worry about the effect on their careers.
The survey of 600 women for the makers of the painkiller Feminax found another 40% had problems concentrating at work.
A Royal College of Obstetricians and Gynaecologists spokesman said 60% of women went to their GP with period problems at some point in their lives.
Experts say, while factors like obesity can be the cause of heavy periods, many menstrual problems have no identifiable cause.
The Feminax study found some women fear their period pains may have had a negative effect on their career.
A third also said the pains made them feel depressed, while 40% also felt they became more moody with friends or partners.
And, even though exercise and a healthy diet are known to relieve period cramps, which are suffered by over 80% of women, a quarter of those surveyed said their cramps stopped them exercising.
A third said that the pain caused them to break their diet.
'May be no cause'
Elaine Maher, from Feminax, said: "We knew that over 80% of young British women suffer, but this really illustrates how much period pains impact upon young women's lives - professionally, emotionally and socially."
The Royal College of Obstetricians and Gynaecologists is holding a meeting later in the year to discuss period problems.
Experts say there are now a range options for the treatment of heavy periods - the main cause of period pain.
In the past, women who had completed their families only had the option of a hysterectomy.
However, they may now opt for endometrial ablation, where the lining of the womb is removed, or to have the hormone treatment Mirena inserted into their womb.
That has led to a fall in the number of hysterectomies performed in England from over 50,000 in 1998, to around 30,000 now.
Peter Bowen-Simpkins, of the RCOG, said: "A heavy period is when it affects a women's life socially or professionally, such that at certain times she is unable to carry on with normal life.
"The Mirena and new safer forms of endometrial ablation have revolutionised our approach to heavy periods.
He added: "Often there is no particular cause to be found. Sometimes a structural irritation in the womb is to blame."