The findings are concerning because young people may be especially receptive to social media influences, and a person's drug use patterns tend to be established in the late teens and early 20s, the study authors noted.
"I've been studying what is influencing attitudes to change dramatically and where people may be getting messages about marijuana that are leading them to believe the drug is not hazardous," principal investigator Patricia Cavazos-Rehg said in a news release from the Washington University School of Medicine in St. Louis.
"As people are becoming more accepting of marijuana use and two states have legalized the drug for recreational use, it is important to remember that it remains a dangerous drug of abuse," added Cavazos-Rehg, an assistant professor of psychiatry at the university.
The researchers noted that in 2011, marijuana use contributed to more than 455,000 emergency room visits, with 13 percent of those for patients aged 12 to 17.
For the study, the researchers analyzed tweets sent between May 1 through Dec. 31, 2013 by a pro-marijuana twitter account. The account has about 1 million followers, making it the largest pro-marijuana Twitter account.
During the study period, the account posted a total of 2,285 tweets, or an average of 11 tweets a day, according to the researchers.
They also found that the account may be influencing young people's attitudes about marijuana. Of the tweets posted by the account, 82 percent were positive about the drug, 18 percent were either neutral or did not focus on marijuana, and 0.3 percent were negative.
The findings were published online June 27 in the Journal of Medical Internet Research.
The U.S. National Library of Medicine has more about marijuana.