Not being able to talk to a pharmacist or a doctor is an obstacle to visiting an online drugstore/pharmacy for roughly a third of online consumers, says a new industry study.

Thirty percent of 2,500 respondents feel that way, according to research firm Greenfield Online's new Digital Drugstore survey.

More than half (57 percent) would visit one of these sites with their doctor's advice, but only one percent have been instructed by their doctor to do so.

Respondents said they would be extremely/very likely to buy from an online drugstore/pharmacy if they could speak with a doctor (via e-mail - 29 percent, via phone - 34 percent) or a pharmacist (via e-mail - 25 percent, via phone - 30 percent). And the vast majority (75 percent) of respondents feel it is very/extremely important to see the doctor's or pharmacist's credentials before seeking their advice.

"Expert medical advice could result in a significant impact on sales for online drugstores and pharmacies," said Rudy Nadilo, chief executive officer of Greenfield.

Of the 40 percent who do visit online drugstores/pharmacies, the most visited sites are: Drugstore.com, 48 percent; Planetrx.com, 34 percent; Mothernature.com, 30 percent; CVS.com, 22 percent; Healthshop.com, 15 percent; More.com, 15 percent; Eckerd.com, 10 percent.

The most purchased items include over-the-counter drugs, personal care products, beauty products and prescription drugs.

The study is part of Greenfield Online's ongoing Digital Consumer series that examines attitudes and usage of the online public and is for sale from Greenfield Online.