Patients buying medicines over the internet will soon be able to look out for a logo assuring them that a site sells safe and genuine medicines.
Patients want to obtain some medicines via the web
A pilot scheme is being launched by the Royal Pharmaceutical Society this week to protect patients.
It comes days after leading cancer doctors warned patients are increasingly turning to the web because drugs are unavailable on the NHS.
The RPS scheme will only apply to sites registered in the UK.
The Medicines and Healthcare products Regulatory Agency, a watchdog which oversees the quality of medicines available in the UK, polices the internet - but can only close down British-based sites which break the law, as it has does not have jurisdiction over those based abroad.
There is concern over consumers buying drugs via the internet because some products are fake and contain ingredients bearing little resemblance to the medicine named on the bottle.
Taking these medicines will do no good to a patient, and may even cause harm.
In August this year, the Lancet medical journal reported the case of a woman who damaged her vision with oral steroids bought online from Thailand.
The 64-year-old woman had taken the drug for four years after making an incorrect self-diagnosis of chronic fatigue syndrome.
Cancer consultant Karol Sikora has also warned that patients who cannot get the latest drugs on the NHS are turning to the web to access what they believe they need.
He said a number of his own private patients had ordered drugs such as Avastin for bowel cancer and Tarceva for lung cancer from a Canada-based internet site.
"These patients are well-informed and they shop around for the cheapest prices," he added.
The RPS scheme cannot outlaw disreputable sites, or the unwanted emails offering cut-price deals on medicines such as the anti-impotence drug Viagra.
Instead, it aims to help those people who want to be able to obtain reputable products, but who do not want to get them via a family doctor, perhaps because they are embarrassed about their condition.
As well as checking individual sites for logos, consumers will be able to go to the RPS's site to check online pharmacists' registration details.
Lynsey Balmer, RPS head of professional ethics, said: "One of the main concerns around the supply of medicines via the internet is that members of the public are often unsure how to distinguish between sites which are operated by a registered pharmacy and sites which operate illegally.
"Patients may believe they are purchasing medicines from a registered healthcare professional, when in fact the supplier has no professional qualifications or healthcare expertise.
"Our policy is that the public benefit from the opportunity for advice from a pharmacist when they have a medicine supplied."
If the RPS pilot scheme is successful, it will be rolled out to all registered internet pharmacies
It is legal for a member of the public to be given a diagnosis and prescription online- if that prescription is signed by a doctor.
But there are no face-to-face meetings, and often not even a phone conversation during this process.