Dubious online pharmacies are putting the health and wealth of customers at risk by operating without proper credentials and lacking even the most basic e-commerce security features.

The claims were made in online brand management company MarkMonitor's latest Brandjacking Index report, a quarterly study which measures the effect of online threats to brands.

Research was based on electronic analysis of 3,160 online pharmacies and 60 million email solicitations from a variety of sources, captured over a four-week period in June.

"The data shows that 'brandjackers' are profoundly exploiting brands, using increasingly sophisticated tactics," said Irfan Salim, president and chief executive at MarkMonitor.

"In the case of the pharmaceutical industry, this poses an outright danger to consumers through questionable practices that indicate counterfeiting and grey markets.

"Caveat emptor on the part of consumers is not a sufficient response. Brand holders must shoulder the responsibility of protecting their brands online from the highly-developed and ever-evolving threats that 'brandjackers' pose."

Researchers found that only four of the 3,160 online pharmacies studied were accredited as Verified Internet Pharmacy Practice Sites, the industry credential that assures consumers of legitimate online pharmacy operations.

Ten per cent of the online pharmacies studied clearly state that no prescription is required to purchase the drugs.

Nearly six out of 10 of these sites were hosted in the US, and 18 per cent in the UK.

As well the health risks associated with self-medicating and taking drugs from an unverified source, over half of the online pharmacies investigated do not secure customer data, putting personal information at risk.

The majority do not use SSL encryption, and more than 20 per cent of post-purchase emails captured in the MarkMonitor analysis contained links to unencrypted customer data.

"Criminals continue to show remarkable adaptability and flexibility as they take advantage of the internet to hijack well-known brands to steal funds, rob identities, launch profit centres for counterfeit and grey-market goods and conduct other nefarious activities," said Frederick Felman, chief marketing officer at MarkMonitor.

Doctors have warned that the use of these online pharmacies can be extremely dangerous for a number of reasons.

As well as the obvious risk of taking drugs from unknown sources, there is the potential danger of self-medicating, such as unpredictable side effects, mis-diagnosis and unknown interactions between different drugs.

Dr Paul Cundy, a GP and member of the British Medical Association's joint IT committee, told vnunet.com: "The problem is that you do not know what you are buying, who you are buying it from or what is in it.

"Counterfeit drugs are prolific. There is no guarantee that what it says on the box is what is in the box. By using online pharmacies customers have none of the regulatory guarantees offered by UK legislation."