Samir Nasri has been warned he could face a four-year ban from football if found guilty of breaking World Anti-Doping Agency (WADA) rules.
The fallout from the bizarre Twitter rant from the Sevilla midfielder - on loan from Manchester City - continues, in which he is claimed to have been hacked by someone obsessed with sexual activity allegations.
Nasri visited Drip Doctors, an intravenous vitamin therapy and lifestyle medical spa based in Los Angeles, which alerted WADA to the potential use of prohibited IV treatments.
"A violation of Article 2.2 of the code could result in a sanction of up to four years," WADA spokesman Ben Nichols said in a statement.
"However, this will depend upon factors such as whether or not the use was intentional and if unintentional, the sanction could be subject to further reductions on the basis of no significant fault or negligence."
Nasri currently has a contract at City which runs until 2019, reportedly in excess of £100,000 a week, but joined Sevilla on a season-long loan deal last August.
Spain's anti-doping agency AEPSAD, the agency for the protection of health in Spanish sport, opened an investigation into Nasri on December 28.