The erotic novel Fifty Shades of Grey has already been blamed for a rise in the number of callouts to the fire brigade for people trapped in handcuffs.

But now a leading doctor is warning that the global best-seller could be linked to an increase in the number of sexually transmitted infections (STIs) among older couples.

Dr Charlotte Jones, the chair of the British Medical Association’s GP committee, said the book had encouraged older people to become “more explorative” in the bedroom, but that there was a risk they were failing to use protection.

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The novel by E L James depicts bondage and sado-masochism and is being made into a film after selling more than 100 million copies. Since the book was published in 2011, there has been a rise in the number of infections in people aged 45 years and older, according to official figures. While the main characters may be in their 20s, Dr Jones suggested some older people appeared to have been inspired to seek out new experiences in the bedroom.

“When it comes to forgetting about safe sex we always think of the vulnerability of young people, but there’s the Fifty Shades of Grey effect where older people are being more explorative but not necessarily remembering to use a condom,” she said.

“Anyone, of any age, going into new relationships should be thinking about safe sex and particularly the role of condoms. People need to take care.”

Figures from Public Health England show that in 2011, there were 1,281 cases of new STIs among people aged 65 and over – not including chlamydia. This rose by more than 7 per cent to 1,374 in 2012.

Among those aged 45 to 64, there were 19,896 cases in 2011 and 20,445 in 2012, an increase of nearly 3 per cent.

In Scotland, there were 210 cases of genital herpes among those aged 50 and over, up from 175 in 2010 and only 47 in 2002. There were 140 chlamydia cases in 2011, up from 127 in 2010 and 48 in 2002.

Harry Walker, the policy and parliamentary manager for the sexual health charity FPA, formerly the Family Planning Association, said his organisation had noticed a similar trend and echoed Dr Jones’s warning.

“Generally speaking there’s a lot more people in older age groups having sex and certainly it is a concern of ours that the 1980s message around condom use – with the HIV campaign – is getting forgotten about or people are getting complacent,” he said.

A spokeswoman for Public Health England said it was “aware of the rise in adults diagnosed with sexual health infections aged 50 years and older... We would strongly urge older adults to go to their local sexual health clinic and get tested, so early diagnosis can be made and promptly treated. We also advise people to use a condom.”