Photos appear to show Sterling passing out unconscious after taking the substance.
A club spokesperson said: "We are aware of the story and intend to speak to the player. Any subsequent action will be taken internally."
Liverpool boss Brendan Rodgers commented on the story after Monday night's game:
“For me it is not something, when you're a professional sportsperson at the top of your game, you shouldn't be doing. It's as simple as that.
“I'll speak to him on it. We want players who are super professional, who are focused on their football – and I know he is, I know he's focused on his football and improving as a player.
“Like I said before, young players will make mistakes, and learn from them – that's what's important.”
