PRIVATE online health services - such as those offering genetic testing, scans and medicines - must be better regulated, experts have warned.
The Nuffield Council on Bioethics said that an explosion of health information on the internet meant people were more empowered than ever before to take action to improve their well-being.
But the council's investigation into online health services found that patients could be vulnerable to misleading claims which cause confusion and anxiety.
Their report warned people to be wary of information on websites where they are unsure who has written it and what their motives might be.
Professor Christopher Hood, chairman of the working party that produced the report, said: "The internet is now often the first port of call for people to find out more about their health. People need to know where they can get accurate health information, how to buy medicines online safely, and how any personal information about their health posted online might be used."
The report said that private DNA tests, which claim to predict future risks of developing diseases, may be "medically or therapeutically meaningless" and give results that are "unclear, unreliable or inaccurate". Body scans may also be sold to try to spot illnesses early. But Nuffield said these often showed up "abnormalities" which actually are harmless and may result in people undergoing unnecessary surgery or other procedures.
The authors welcomed the fact that no online firms appear to still be offering full body scans, but said there were still radiation risks associated with scanning individual body parts.
They also stopped short of calling for such tests and partial body scans to be banned, saying there was a lack of evidence of widespread harm to patients.
The report also looked at issues such as buying medicines over the internet and the creation of patient health records online in places like Google Health and Microsoft HealthVault. It warned that buying medicines online could be dangerous, as pharmacies based outside the UK could deliver "harmful, fake or low quality products".
Figures from 2008 show that around two million people in the UK were regularly buying medicines online.
The experts called for regulators, such as the Medicines and Healthcare products Regulatory Agency (MHRA) and the Advertising Standards Association, to take on a bigger role in monitoring the sale of scans, tests and drugs direct to the consumer.
Prof Hood said: "We recommend that all websites offering health information and advice should state where the information originates and what it is based upon, who wrote it, and how the author or organisation is funded.
"Advertisements for medicines and products should also be clearly distinguished from other types of information."The results of personal DNA testing and body scanning are often hard to interpret, unreliable and may cause people unnecessary anxiety.
"Better regulation is needed to ensure people are fully aware of the limitations of these services."
A British Medical Association Scotland spokeswoman said: "The internet can be a fantastic source of health information, but does need to be used very selectively … people should be extremely sceptical about any sites that promise miracle cures or demand payment."
A Scottish Government spokeswoman said: "Through NHS Inform (the NHS Scotland website] people in Scotland have a single place to turn to for all of their health information needs. It allows people to access trusted information where they need it, when they need it."