The NFL Players Association filed a grievance against the NFL's teams and the NFL Management Council for forcing players to sign waivers when being prescribed Toradol.
Toradol is a nonsteroidal anti-inflammatory drug that is used as a short-term treatment for moderate to severe pain.
It is usually used following surgery, but it can also be applied for other causes of pain.
The NFLPA is seeking to make null and void previously executed liability waivers players were required to sign before team physicians issued Toradol to them.
The NFLMC assured the NFLPA earlier in the season that the collective bargaining agreement instructed teams that players could not be asked to sign such waivers, but this direction has yet to be given to the physicians, who are also bound to the terms of the CBA since they are "agents of NFL clubs."
Toradol has been known to increase risk of life-threatening heart or circulation problems, including heart attack or stroke, or increase your risk of serious effects on the stomach or intestines.
The players association said in a statement Wednesday, "If an NFL Club physician believes a player would be placed at an unacceptable medical risk by using Toradol as part of the care and treatment of an injury, or if the club physician is concerned about the long-term effects of such use, the team's medical staff should inform the player of that opinion and refuse to administer Toradol.
"The NFL Club physician should not administer Toradol and require that a player sign a waiver of liability before doing so. If, on the other hand, there is no such concern on the part of the club's medical staff, it should advise the player that the use of Toradol is appropriate."