Salas tested positive for a performance-enhancing substance, the commissioner's office said. His suspension will start today.
There were just three suspensions last year under the major league program: New York Mets pitcher Yusaku Iriki, former Arizona pitcher Jason Grimsley and Mets reliever Guillermo Mota, who is serving his 50-game penalty at the start of this season.
Salas, a 28-year-old right-hander, is 1-1 with a 3.95 ERA in 15 appearances this season. He will lose about one-third of his $382,000 salary.
"The Tampa Bay Devil Rays fully support Major League Baseball's drug testing policy. We will do all we can to help Juan get his career headed back on a positive course,'' the team said in a statement.
Tim Corcoran was called up from AAA Durham and will take Salas's spot on the 25 man roster. Struggling relief pitcher Ruddy Lugo was optioned to AAA Durham as well. Chad Orvella will take up his spot in the bullpen.
Tyler Hissey contributed to this story