London, Sep 19 (IANS) Millions of women now could be freed from the monthly misery of premenstrual syndrome (PMS) by taking a tiny dose of a common drug for a few days.

A major breakthrough has uncovered the cause of the debilitating cramps and mood swings that blight most women, reports express.co.uk.

Giving them a low dose of the common anti-depressant Prozac could stop PMS for good.

For the first time neuroscientists have found an organic cause for the condition when the levels of a female sex hormone changes.

Researchers at the University of Birmingham, led by Thelma Lovick, have shown that premenstrual-like symptoms can be triggered in female rats by a change in the level of secretion of one of the female sex hormones that normally occurs towards the end of the menstrual cycle in women.

In tests, the team found that PMS could be prevented by giving low doses of Prozac which is also known as fluoxetine.

Lovick said: "All that would be needed for countless women to benefit from what could be a simple and accessible treatment, involving a drug that is already in widespread use, is clinical tests to refine it and identify the optimal dosing strategy."

PMS causes pain and upset for millions of women worldwide.

Although not all women show all the symptoms, around 75 percent of women are thought to experience some of them.

These can include anxiety, mood swings, tiredness, depression, headaches, feeling bloated and pains in the joints.