(CNN)Golden Tate says he and his wife are trying to have a baby.
As a result, the New York Giants receiver says he was prescribed fertility drugs in April.
"Just days later I discovered it contained an ingredient that is on the league's banned substance list," he said in a statement on Twitter Saturday. It's not clear at this point what the ingredient was that got Tate in trouble.
Tate is now facing a four-game suspension, according to the NFL's website.
Tate says he's always taken great pride in playing football "the right way" and has never had issues with the league's banned substance policy. Upon finding out about the ingredient in the fertility drugs, he says he "immediately discontinued use" and reported the situation to the NFL and spoke with his coaches and general manager.
"The treatment this past April had no effect on the upcoming season, and I did not, and could not have undergone this treatment in April for any competitive advantage," his statement read.
Tate's statement also said he knew the initial suspension was imminent, but he and the Giants are "confident in the facts" and are awaiting his appeal.
Giants head coach Pat Shumur said in a press conference Saturday that Tate has been "very honest" with the Giants organization about the situation. He also said the team found out about the medication after Tate was traded to the team in March.
Because Tate hasn't officially been suspended, Shumur said "it's business as usual" for him right now.
"He's out there practicing and getting ready to play," Shumur said. "This really is between him and the league at this point. As an organization, we'll deal with it as it comes down the road."
CNN has reached out to Tate's agent, but has not heard back.
The NFL season officially starts September 5. Preseason games begin in August.
This will be Tate's 10th season in the NFL. He was drafted out of Notre Dame by the Seattle Seahawks in 2010. He played for the Detroit Lions and the Philadelphia Eagles before being traded to the Giants in March.