What do Internet users most want to do after being diagnosed by a doctor? They seek more information—and many turn to the Web.

Nearly one-half of Internet users responding to a survey by About.com said they used a search engine to find more data about their specific medical condition. Another 20% went to health Websites to get more info, and others used search engines to find out more about treatment options and prescription drugs. Just 35% of Internet users simply trusted their doctor without looking to the Web.

Marketers can capitalize on this hunger for health information by using their ads as an educational tool. More than four in 10 Internet users told About.com that pharma ads made them aware of treatment options and educated them about symptoms and conditions; 17% felt like they could speak more knowledgeably with their doctor because of pharmaceutical advertising.

When surveyed about what would catch their attention, Internet users were most likely to say info about specific conditions (29%) and the side effects of medications (28%). Notably, Web users were more interested in medical data than free trial offers (18%).

After seeing healthcare ads, 38% of respondents said they talked with their doctor and 36% researched the advertised drug online. In addition, 13% of Internet users visited the pharmaceutical company’s Website.

According to Harris Interactive, 78% of US adult Internet users had searched for health information online as of 2009. That’s a big opportunity for pharmaceutical marketers looking to educate consumers through advertising.