Chicago Bears receiver Brandon Marshall has heard of various ways that players try to get an advantage on the field -- including erectile dysfunction medication.
"I've heard crazy stories. I've heard guys using like Viagra," Marshall said. "Seriously, because of the blood ... I don't know, some crazy stuff.
"It's kind of scary with some of these chemicals that are in some of these things, so you have to be careful."
NFL spokesman Greg Aiello said Viagra is not a banned substance and declined further comment.
The issue came up Wednesday because sources have told ESPN that Richard Sherman and Brandon Browner of the Seattle Seahawks, who play at Soldier Field on Sunday, tested positive for Adderall. Both appealed and their hearing will not be held this week, sources told ESPN, so both are expected to be able to face the Bears.
"I don't know too much about Adderall," Marshall said. "I know guys ... it's such a competitive league ... and guys try anything just to get that edge."
Marshall said he has never taken any substances to help him get an advantage. "I'm fortunate enough to be blessed with size and some smarts to give me my edge, but some guys ... they'll do whatever they can to get an edge."
Sherman and Browner face possible four-game suspensions.
"It's tough," Marshall said. "Anytime you take anything over the counter, if you don't approve it with your training room, you can get popped that quick. It doesn't matter if it's DayQuil, NyQuil, any type of cough medicine. Even Hall's.
"It's a really strict program that the NFL has. Some of it is fair, but it kind of puts you in a tough spot as a professional athlete. The only thing you'll see is getting busted for PEDs, but it could be something over the counter for a little sickness. You just have to be on top of your P's and Q's."
Information from The Associated Press was used in this report.