Women who take common anti-depressants to counter the impact of menopause may have a 76 per cent higher risk of broken bones, scientists warn.
The risk appears to last for several years after women take the drugs, leading to calls for doctors to reduce the period for which they are prescribed.
For many women, the onset of the menopause triggers mood changes and depression, and each year thousands are prescribed a type of anti-depressant called SSRIs - selective serotonin reuptake inhibitors, the best known of which is Prozac.
The drugs are also sometimes prescribed to help women cope with other effects of the menopause, such as irritable bowel syndrome, hot flushes and night sweats.
But new research suggests a side effect of the drugs may be a weakening of the bones.
SSRIs are among the most commonly prescribed drugs in Britain. Some 30 million prescriptions for them were given out in England last year, at a cost of £74 million (NZ$170 million).
There are no figures for how many are given to menopausal women, but it is thought that some doctors prefer to prescribe anti-depressants rather than hormone replacement therapy, fearing HRT can increase the risk of heart problems.
But the balance is beginning to swing back in favour of HRT, with new NHS guidelines expected to tell doctors to stop excluding certain women from access to the drugs.
Researchers from Northeastern University in Boston analysed data from 370,000 American menopausal women over 12 years. Of these, 137,000 took SSRIs, including fluoxetine, which is known as Prozac, as well as hydrobromide, oxalate, fluvoxamine, paroxetine and sertraline.
The researchers compared this group with 236,000 women who took indigestion medications over the same period.
Among those who took the SSRIs, the rate of fractures was 76 per cent higher one year after starting treatment, 73 per cent higher after two years and 67 per cent higher after five years.
The researchers stressed that their study was purely based on statistics, so they could draw no definitive conclusions about cause and effect. But previous research has suggested that anti-depressants may alter the way bones grow, making them thinner and weaker.
The authors, led by injury prevention expert Professor Matthew Miller, wrote in Injury Prevention, part of the British Medical Journal group: "SSRIs appear to increase fracture risk among middle-aged women without psychiatric disorders, an effect sustained over time, suggesting that shorter duration of treatment may decrease this.
"Future efforts should examine whether this association pertains at lower doses."
The National Institute for Health and Care Excellence is expected to publish guidelines later this year telling NHS doctors to stop denying HRT to menopausal women who have high blood pressure.
Specialists have long complained that many are being unfairly denied HRT and left to deal with the effects of the menopause unaided.
- Daily Mail