Superdrug has become the first high street pharmacy to offer a £10 'morning after' pill that could slash soaring rates of sexually transmitted infections (STIs).

The preventative antibiotic – known as DoxyPEP – has been shown to cut the risk of syphilis and chlamydia by up to 80 per cent, when taken within 72 hours of having sex.

In June, the British Association for Sexual Health and HIV published the UK's first national guidance on the drug for preventing syphilis in at risk populations including gay and bisexual men.

But experts said this didn't go far enough and called on health chiefs to make the medicine more widely available across the UK and US.

STI rates have surged in recent years, with changing sexual behaviours and treatment resistance believed to be behind the worrying trend.