Liverpool have said they are aware of footage of striker Raheem Sterling apparently taking nitrous oxide, though manager Brendon Rodgers defended his player's character.
Pictures published on The Sun's website appear to show the England international passing out unconscious after taking the substance, described as a legal high.
A club spokesperson said: "We are aware of the story and intend to speak to the player. Any subsequent action will be taken internally."
Rodgers said he disapproved of Sterling's actions but hailed his player as "super-professional" while on the job.
"It is something that when you are professional sportsperson at the top, I don't think it is something you should be doing," Rodgers said in a news conference. "It is as simple as that. But I will speak to him. We want players here who are super-professional and focused on their football. He very much is."
The Liverpool manager was pleased Sterling was not distracted by the off-field incidents as he opened the scoring in Monday's 2-0 win over Newcastle.
"He is a young kid who is in the spotlight now so he knows the demands of being a top class player and a top class professional," Rodgers said. It is not just on the field, it is off it as well. I will speak with him and we will move on.
"He is very valuable. He is a kid who's non-stop, he wants to learn and improve himself. I thought he was outstanding tonight. Wonderful skill and ability for his goal. He will be disappointed he didn't get three goals. He is always a threat."
EXCLUSIVE: Raheem Sterling 'inhales hippy crack' before big game. Watch the video here http://t.co/7Uab1vH9JW pic.twitter.com/CTPrShYdoy
- The Sun (@TheSunNewspaper) April 13, 2015
Former Liverpool defender Jamie Carragher believes Sterling has been guilty of naivety on occasion over the last year, with regard to his publicised problems away from the field, but added that the youngster can treat the experience as a learning curve.
"Whether you're a Premier League footballer or you're a 20-year-old kid or whatever, you make mistakes at that age. I did and I'm sure we all do," Carragher said on Sky Sports.
"It's just important he learns from it because Raheem Sterling, for how good a footballer he is, needs to be on the back pages, not on the front pages and that's a problem for him in these last few months.
"But he's a young player, he made a few mistakes and hopefully in years to come he learns from them."
The matter comes at a time when considerable controversy surrounds 20-year-old Sterling following the apparent breakdown of contract talks with the club. Sterling risked the wrath of supporters by admitting he had rejected a £100,000-per-week deal in a recent interview that was not sanctioned by the club.
Earlier, Liverpool declined to comment on a photograph that emerged Sterling appearing to smoke a shisha pipe.
A picture of Sterling with the pipe became public via social media platform Snapchat over the weekend. The photo was overlaid with a caption that read "1 down 3 to go," implying that there were more pipes to be smoked.
The Sunday Mirror claimed that Sterling had inhaled on the pipe during a night out with friends in Liverpool. However, it is not clear whether Sterling actually smoked the shisha -- a water-pipe in which fruit-scented tobacco is burned using coal -- or when the photo was taken.
Sterling has also made no public comment on the photograph.
Information from Press Association was used in this report.