The perils of online self-diagnosis are more pertinent for people who have trouble handling uncertainty, a psychologist has warned.
"Cyberchondria" - the online counterpart of hypochondria - from online health searches is worse for those who fear the unknown, a study suggests.
People who have an "intolerance of uncertainty" engage in "safety behaviours" - such as checking symptoms online - to reduce their distress.
But scouring the web for medical information has the potential to lead to greater levels of uncertainty, researcher Dr Thomas Fergus said.
The assistant professor of psychology and neuroscience at Baylor University in Texas, United States, said: "If I'm someone who doesn't like uncertainty, I may become more anxious, search further, monitor my body more, go to the doctor more frequently - and the more you search, the more you consider the possibilities.
"If I see a site about traumatic brain injuries and have difficulties tolerating uncertainty, I might be more likely to worry that's the cause of the bump on my head."
His study, published in the journal Cyberpsychology, Behaviour and Social Networking, examined levels of health anxiety and intolerance of uncertainty in 512 healthy adults.
He found that the frequency of searching for medical information on the internet and health anxiety grew increasingly stronger as intolerance of uncertainty increased.
The results showed that people who have difficulty tolerating uncertainty are "especially likely" to experience cyberchondria.
He wrote: "An individual who searches for medical information on the internet will likely be presented with multiple explanations for symptoms, some of which might be catastrophic explanations. The present results indicate that individuals with high intolerance of uncertainty are especially likely to experience health anxiety in response to such internet searches."