Consumers who rely on the user-edited Web resource Wikipedia for information on medications are putting themselves at risk of potentially harmful drug interactions and adverse effects, new research shows.

Dr. Kevin A. Clauson of Nova Southeastern University in Palm Beach Gardens, Florida and his colleagues found few factual errors in their evaluation of Wikipedia entries on 80 drugs. But these entries were often missing important information, for example the fact that the anti-inflammatory drug Arthrotec (diclofenac and misoprostol) can cause pregnant women to miscarry, or that St. John's wort can interfere with the action of the HIV drug Prezista (darunavir).

"If people went and used this as a sole or authoritative source without contacting a health professional...those are the types of negative impacts that can occur," Clauson told Reuters Health.

Wikipedia is an online, free encyclopedia covering millions of topics in more than 250 languages. Users add and edit content themselves. Clauson and his colleagues decided to investigate the accuracy and completeness of drug information on Wikipedia given that one third of people doing health-related Internet searches are looking for information on over-the-counter or prescription drugs, and that a Wikipedia entry is often the first to pop up with a Google search.

The researchers compared Wikipedia to Medscape Drug Reference (MDR), a peer-reviewed, free site, by looking for answers to 80 different questions covering eight categories of drug information, for example adverse drug events, dosages, and mechanism of action.

While MDR provided answers to 82.5 percent of the questions, Wikipedia could only answer 40 percent. Answers were less likely to be complete for Wikipedia, as well. Of the answers the researchers found on Wikipedia, none were factually inaccurate, while there were four inaccurate answers in MDR. But the researchers spotted 48 errors of omission in the Wikipedia entries, compared to 14 for MDR.

"I think that these errors of omission can be just as dangerous" as inaccuracies, Clauson told Reuters Health. He pointed out that drug company representatives have been caught deleting information from Wikipedia entries that make their drugs look unsafe.

The researchers did find that after 90 days, the Wikipedia entries showed a "marked improvement" in scope.

Wikipedia can be a good jumping-off point for Internet research, Clauson said, but shouldn't be seen as the last word on any topic-and should certainly not be used as a resource by medical professionals. "You still probably want to go to medlineplus.gov or medscape.com for good quality information that you can feel confident in," he said.