Adults over 50 who use a type of antidepressants are at double the risk of bone fractures, a study suggests.
Bone fractures were more common in SSRI users
The Canadian researchers focused on selective serotonin reuptake inhibitors (SSRIs) including drugs such as Prozac and Seroxat.
The Archives of Internal Medicine study found SSRI use was linked both to a greater number of falls, and a reduction in bone density.
UK experts said more evidence was needed to confirm the link.
The team from McGill University in Montreal, Quebec, studied 5,000 people over 50 over five years.
They looked at their use of SSRIs, bone mineral density in the lower spine and hip and the number of falls they had.
The researchers found 137 people, with an average age of 65, used SSRIs every day.
They were found to have double the risk of falls, with injuries mainly affecting the forearm, ankle and foot and hip.
The higher the antidepressant dose a patient was on, the higher their risk of falls, the research found.
In addition, those who took SSRIs daily had 4% lower bone mineral density in the hip than those who did not and a 2.4% decrease in the lower spine.
Risks versus benefits
Serotonin is a chemical known to play a key role in regulating mood.
However, serotonin receptors and transporters have also been found in bone cells, where they are thought to influence bone formation.
The authors, led by Dr Brent Richards, said: "Elderly persons are at increased risk of developing osteoporosis and depression.
"Daily SSRI use in this population to treat depression may increase the risk of subsequent fracture.
"These risks must be balanced against the benefits gained by the treatment of depression with SSRIs.
"In light of the high rate of SSRI use among the general population, and among elderly persons in particular, further studies are needed to confirm our findings."
Sophie Corlett, policy director for the mental health charity Mind said: "Here is further evidence that psychiatric drugs can carry significant costs for those who take them.
"Talking therapies are recommended as the preferred treatment for depression for most people.
"But because talking therapies are not available in much of the country, GPs are being forced to prescribe drugs when alternative treatments would be preferable.
"Sadly, this is particularly the case for older people, who, despite being more at risk of osteoporosis have particular problems gaining access to talking therapies than those in other age groups."
Marjorie Wallace, chief executive of the mental health charity Sane, added: "While most people have to wait months or years for talking therapies, we must balance the relatively small and unproven risks of decreased bone density due to medication against the significant and long-proven risks associated with untreated depression."
But a spokeswoman for the National Osteoporosis Society said: "While this was a large study, only a small number of subjects were taking these drugs and more evidence is needed in order to confirm the findings.
"Whether it was the drugs themselves or some other factor, such as risk of falling, common to those in the study that caused the increase in fractures is uncertain."
She said anyone with concerns should contact the society or speak to their doctor.