Matthews was not connected to HGH or other performance enhancing drugs directly, as Manning, Ryan Howard, Ryan Zimmerman and others were, but pharmacist Charlie Sly claimed in undercover videos to have provided him with painkillers.
The Huffington Post summed up the claims:
Sly also says that he provided Clay Matthews, Green Bay’s Pro Bowl linebacker, with the prescription painkiller Percocet to help him deal with pain before at least one game. He also brags in one undercover video that Matthews texted him in an attempt to obtain Toradol, a powerful painkiller that is banned in many countries but not in the United States.