Mini doses of Prozac could end the monthly misery of PMS, scientists believe.
They say that the irritability and mood-swings of pre-menstrual syndrome are caused by plummeting levels of a hormone that keep a lid on emotions.
Prozac raises levels of this natural sedative and so should stop a woman’s mood fluctuating in the run up to her period.
The doses given would be much smaller than those used to treat depression – cutting the risk of the side-effects that have dogged Prozac’s use in psychiatry.
Bristol University researcher Thelma Lovick said: ‘Pre-menstrual syndrome is an enormous problem.
‘Something like 80 per cent of women suffer in some way.
‘And it’s not just women – it’s their partners, their families and their workmates.
‘It is a terribly British thing to just brush it under the carpet and say “It’s women’s trouble”.’
‘It is caused by hormones and there is something we can do about it. And everybody would benefit.’
Dr Lovick, who did her research with colleagues in Brazil, said that the symptoms of PMS seem to be caused by a sharp fall in levels of the hormone progesterone around a week before a woman menstruates.
Normally, a waste product of progesterone called allopregnanolone, or allo, acts as a natural tranquilliser and keeps the brain circuits that control emotions calm.
When progesterone falls, the amount of this sedative falls and emotions run riot.
Dr Lovick, who has likened the brain changes caused by lack of allo to those experienced by a heroin addict denied their fix, has shown that Prozac raises levels of allo.
Given to rats, the drug banished the increased sensitivity to pain and stress they normally occurs at the same point in their cycle as women experience PMS.
Dr Lovick says that given to women, Prozac could ease the anxiety and irritability that often occurs ahead of a period.
The scientist, who has published her work in the British Journal of Pharmacology, said: ‘If you have got PMS, you get irritated by things that wouldn’t annoy you at other times.’
Dr Lovick hopes the treatment will also ease other symptoms of PMS, including bloating and lethargy, but won’t know until the drug has been trialled on women.
She hopes to start tests on women soon.
Regular strength Prozac lifts depression by raising levels of ‘feel good brain’ chemical serotonin but can cause problems from loss of libido to suicidal thoughts and self-harm.
Using much lower doses, around a fifth of those used to treat depression, would not have any effect on serotonin and so the odds of side-effects should be reduced.
In addition, women would not take the drug every day. Instead, they take one a day for a week from when they first show signs of PMS.
Michael Dooley, a consultant gynaecologist and spokesman for the Royal College of Obstetricians and Gynaecologists, said that some doctors already prescribe low-dose Prozac for PMS.
Women are anxious about taking the pills but the results have been ‘fantastic’.
But Linda Gask, a member of the Royal College of Psychiatrists, warned of the possible side-effects.
She said: ‘The problem is that when you take medication, you are going to have side-effects.
‘With a low dose, side-effects will be less likely but I think most psychiatrists are concerned about medicalising something that you could probably find other ways of managing.’
Although PMS is often viewed as a minor inconvenience, it affects around 80 per cent of women - and up to 40 per cent of those say it damages their quality of life.
In extreme cases, women can become violent and suffer from severe depression.
There is also an economic impact, with research suggesting that time off and loss of productivity due to the syndrome annually costs employers around £3,000 per female employee.
