For all the benefits that search engines and online support groups have brought to patients – especially in an era of shrinking health budgets and stretched front-line services – the collision of health care and social media has highlighted a number of thorny issues. The internet is notoriously patchy as a source of health advice, for a start, with nervous users often vulnerable to "cyberchondria", the kind of hysteria that can transform an innocent mole into a malignant tumour or a minor rash into a life-threatening bout of meningitis.

Among the more pernicious phenomena that put today's online patients at risk is a pattern of behaviour known as "Münchausen by internet" (MBI), an online variant of Münchausen syndrome. Where old-fashioned, non-digital Münchausen sufferers feign illnesses in hospitals and GP's offices, MBI involves posting faked stories on internet support forums in an attempt to elicit sympathy and support from other users.

MBI, a term coined by the US psychiatrist Marc Feldman but still unrecognised by the latest Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), has gained widespread media attention through a series of high-profile cases, one of the most recent being that of a teenage girl who, it was revealed last November, adopted the fictitious persona of a mother caring for her cancer-stricken daughter, stringing along the Macmillan cancer support forum for more than two years before the deception finally unravelled.

MBI falls into the hazy nether-region between the wider culture of online trolling and a genuine psychiatric condition. Whether a user lying on health forums is motivated by simple malice or deeper psychiatric issues, the fact remains that it's a lot easier to mislead a supportive online community than a doctor and the consequences are more serious. Whereas doctors are equipped to deal with hypochondriacs and fakers, people who post on forums are often patients themselves and considerably more vulnerable to abuses of trust.

What's more, the vast, faceless mass of anonymous online communities makes it incredibly difficult to pick out the fakers from their genuine counterparts. Barring the use of plagiarism software to spot suspicious patterns or bolstering privacy settings, which seems to defeat the purpose of public forums, the best defence is a sharp-eyed community, with specialists also calling for formal recognition of MBI as a pattern of behaviour and a more proactive social media stance from health-care authorities. Unfortunately, the internet seems to be throwing up issues such as MBI faster than anyone is equipped to address them. In the meantime, the best advice for health forum users will remain depressingly basic: tread carefully and carry a big grain of salt.

The article can be read in full here. Chris Lo is a senior technology writer for the NRI Digital network.