Few American adults have bought prescription drugs through the internet, despite rising drug costs and increased pressure to import cheaper drugs from abroad, according to a new study released Sunday.

Four percent out of 2,200 U.S. patients surveyed said they purchased their medicines online, and nearly all of them said they would do it again in the future, the study showed.

The Pew Internet Project found most of those who bought drugs over the internet - about 75 percent - said they used them to treat a chronic condition, including arthritis, high blood pressure and other diseases.

The rest, about 25 percent, said they bought drugs to help lose weight, improve sexual performance or some other purpose, according to the independent think tank’s study.

About 63 percent of all internet users surveyed said they received spam e-mail for sex-related drugs like Pfizer’s erectile dysfunction drug Viagra, while 55 percent said they received spam for other prescription medicines.

The telephone survey, conducted in May and June, has a margin of error of plus or minus 2 to 3 percent. The Pew Charitable Trusts funded the survey.

About 26 percent of Americans used the internet to research information about prescription drugs, but most respondents said they did “not fully trust” the online marketplace.

More then 60 percent said they thought drugs bought from internet vendors were not as safe those purchased from a local drug store, while 20 percent said they were equally safe.