An investigation has been launched into online pharmacies after a number of websites freely prescribed antibiotics to reporters.
The General Medical Council (GMC) launched the probe based on evidence collected by BBC Radio 5 live, and said that "the overprescribing of antibiotics risks the health of us all".
The investigation looked at 17 UK-based pharmacies selling antibiotics online and found that, while most appeared to operate within National Institute for Health and Care Excellence (Nice) guidelines, one case issued three prescriptions in the space of 24 hours to a BBC reporter.
It comes as the NHS urges health professionals to avoid overprescribing antibiotic drugs in a bid to stem growing resistance to them. It is estimated that this could kill 10 million people by 2050.
During the BBC investigation, one online pharmacy offered a choice of antibiotics to a reporter who asked for treatment for a dental infection.
But while Nice guidelines state the drugs should only be prescribed for patients with a significant facial swelling or a condition that shows their immune system has been damaged, neither of those things were brought up in the reporter's online application.
The clinic then issued the same reporter with two more prescriptions in the next two days, one each for a swollen ear and for a urine infection.
Treated.com was also on the list and issued a reporter with a prescription for the antibiotic Metronidazole for £38 - around £30 more than the cost of an NHS prescription.
Posing as a male with an ear infection, the reporter first had to fill in a questionnaire including questions about whether he had symptoms of a vaginal infection.
The company has since said it has deactivated consultations for ear infections because of a "system glitch" and will regularly review treatments provided.
But it insisted that not all prescriptions are approved and added that, while a face-to-face consultation is the ideal method of making a diagnosis, its service is aimed at people who need a more immediate convenient solution.
GP Faye Kirkland, who is also a freelance BBC reporter, said: "They're not even the kind of antibiotics that I would even consider giving to a patient because they don't kill the bugs that typically cause the problem."
GMC boss Niall Dickson said: "Our prescribing guidance makes it absolutely clear that doctors may prescribe only when they have adequate knowledge of the patient's health, and are satisfied that the medicines serve the patient's needs.
"The guidance also makes it clear that they should take account of clinical guidelines published by established organisations with appropriate expertise, such as Nice."
A spokesman for the council added: "We will investigate and would request that the BBC team provides us with all of the evidence it has gathered to assist us with our inquiries."
There has recently been heightened concern surrounding the overprescription of antibiotics since the The Review On Anti-Microbial Resistance, commissioned by former prime minister David Cameron in 2014, concluded that more than 10 million people a year would die by 2050 unless steps were taken to reduce the quantity of drugs being used.
Lord Jim O'Neill, who led the review, said the BBC Radio 5 live findings were "disturbing" and believes antibiotics should not be prescribed at all "unless it's gone through a set of clear diagnostic tests".
But he highlighted that patients must also take responsibility, adding: "Much of the time when antibiotics are prescribed they are not necessary and we need to stop demanding (them) from doctors and circumnavigating and going on the internet to use them, thinking 'I'm miraculously saved'.
"Some illnesses still can't be saved by an antibiotic."
A spokeswoman from the Department of Health echoed the GMC's call for tightening the use of antibiotics by bringing down demand.
She said: "We want to make sure that antibiotics are only used when they are really needed. Websites selling prescription medicines must be registered pharmacies. If they are not, they can be prosecuted.
"We are working on raising public awareness of the fact that antibiotics are not effective for common illnesses such as most coughs and colds. The aim is to reduce demand for antibiotics in the first place.
"We are also raising awareness of the devastating impact that increasing antibiotic resistance will have on modern medicine unless we curb the inappropriate use of antibiotics. We applaud the work of GPs in reducing prescribing of antibiotics in the UK recently."