Women can now buy the prescription-only contraceptive pill from an officially-sanctioned UK website without seeing a doctor.
The move has led to fears that under-age girls will go online and buy the drug.
Organisers say they will try to limit sales to over-18s but admit there is no way of stopping younger girls from circumventing the system.
Medical experts are worried that without proper checks on a woman’s weight, blood pressure and medical history, there could be complications.
The pill can cause a rise in blood pressure and women with a history of blood clots are often advised against taking it.
The website, DrThom, is registered with the statutory watchdog, the Healthcare Commission. It is the first UK-based site to sell the drug, although international sites have been selling it for some time.
Initially the site will only sell the pill to women who have previously taken it. But there are plans to widen availability to new users “very quickly”.
Doctors are worried. London GP Trevor Stammers said: “I am sure it will only be a matter of time before someone has a thrombosis or embolism as a result of using that service.
“The contraceptive pill is not a Smartie. You need to be monitored when you are on it.”
He added: “One knows from other areas of internet use that you can never know who is on the other end of the line.
“There seems to be an open door for abuse of the system by those who are not over 18.”