There is some debate as to whether there is such a thing as premenstrual dysphoric disorder (PMDD), and it's important to rule out other mental health problems first. The symptoms for PMDD are very similar to PMS, but the difference is in their severity. They have a significant impact on a woman s ability to function socially or at work, and may also lead to suicidal thoughts.

The timing of the symptoms in relation to the menstrual cycle is crucial to the diagnosis, just as it is for ordinary PMS. PMDD is thought to affect between three and eight per cent of women of childbearing age. The problem is also called simply severe premenstrual syndrome.

Historically, many feminists have opposed the diagnosis because they believe it has a negative effect on general attitudes towards women. The condition hasn't yet been included in the main body of the DSM-IV (The American Psychiatric Association's diagnostic and statistical manual of mental disorders). But it is listed in the Appendix, for research purposes. In the UK, recognition lies in the fact that the SSRI antidepressant fluoxetine (Prozac) is licensed to treat it. There's some concern that women might be diagnosed with this condition when it's more likely that they are already experiencing another mental health problem, such as depression or anxiety, which is heightened by PMS.