Health chiefs are investigating 30 doctors in the UK over prescribing drugs via the internet.
The General Medical Council is currently dealing with the cases – which include 19 GPs – on suspicion of unsafe prescribing.
Several deaths have been linked to patients obtaining strong medications this way, prompting coroners to write to health authorities at least two cases, GP magazine Pulse reports.
The watchdog warned that doctors are handing out addictive painkillers online without carrying out the proper medical checks
It comes just days after the care regulator found that almost half of online GP firms are unsafe.
A report by the Care Quality Commission warned many online doctors are handing out addictive painkillers and antibiotics without carrying out appropriate checks.
Others failed to pass on prescription details to patients’ regular GPs while some did no checks to ensure patients were over 18 before prescribing potentially harmful medications.
People are increasingly turning to online doctors because they face weeks of waiting for face-to-face appointments with their GPs
Last night the GMC, which regulates doctors, would not release details of the cases but confirmed it was working with other regulators to address patient safety concerns.
A spokesman said: ‘In recent years the use of digital health services has expanded rapidly.
‘While they may present a convenient way for some patients to access healthcare, it is important that these services do not compromise patient safety.
‘We take any concern linked to inappropriate practice of telemedicine very seriously.’
Watchdogs have voiced concerns over the rise of online prescribing, which increasing numbers of patients are turning to rather than waiting weeks to get an appointment with their own GP surgery.
Patients can choose to have consultations over the internet using a webcam, or Skype, while others simply allow patients to fill in a form that is checked by doctors before they are given a prescription.
In addition to UK-based services, the CQC and the Medicines and Healthcare products Regulation Agency say patients are also getting prescriptions from abroad.
Experts are concerned it is fuelling growing addictions to strong painkillers. Hospital admissions in England for opioid abuse have nearly doubled in the last decade.
A report by the Care Quality Commission warned many online doctors are handing out addictive painkillers and antibiotics without carrying out appropriate checks
Figures showed the number of cases involving overdoses from strong painkillers such as codeine, morphine and oxycodone have soared 85 per cent to 20,130 last year.
Dr Andrew Green, of the British Medical Association’s general practitioners committee, told Pulse: ‘In comparison to the highly regulated world of general practice, these providers seem to work in a ‘wild west’ beyond the reach of many regulators.
‘Of particular concern are prescriptions for drugs with potential for dependence, such as opioids, and for antibiotics, whose overuse threatens us all.’