Twitter could become a useful source of information about health, according to US researchers.
Two John Hopkins University computer scientists studied 1.5 million health-related tweets between May 2009 and October 2010.
It provided an insight into how Twitter users viewed a range of illnesses and how they went about treating themselves.
It also showed that many chose the wrong drugs to tackle common ailments.
"Tweets showed us that some serious medical misperceptions exist out there," said PhD student Michael J. Paul who helped run the research project.
"We found that some people tweeted that they were taking antibiotics for the flu," he said. "But antibiotics don't work on the flu, which is a virus, and this practice could contribute to the growing antibiotic resistance problems."
To find health-related posts among the billions of messages sent during the study period, the researchers devised a special filtering tool.
The computer program was taught to disregard phrases that did not really relate to health, even though they contained a word commonly used in a health context - such as "high price of gas is a headache for my business".
In about 200,000 of the health-related tweets, publicly available information meant the researchers could identify which US state they came from.
This allowed them to identify health trends across the US.
"We were able to see that the allergy season started earlier in the warmer states and later in the Midwest and Northeast," said Professor Mark Dredze.
But both scientists acknowledged that there were limitations to what they could discover about health issues via Twitter.
Often they found that tweeters did not comment more than once on a particular ailment.
"We could only learn what people were willing to share and we think there's a limit to what people are willing to share on Twitter," said Mr Paul.