Robert Snodgrass has been given a one-match ban and fined £30,000 for misconduct towards UK anti-doping officials.
The West Ham midfielder was charged by the Football Association (FA) in March for allegedly using "abusive and/or insulting and/or improper" language towards the officials when they visited the Hammers' training ground on February 6.
The Scotland international requested a personal hearing to challenge the charge, but the decision was upheld by an independent regulatory commission.
"The player has been given a one-match suspension, which is not currently active whilst he considers his right of appeal, and fined £30,000," the FA said on Tuesday.
Snodgrass has made 30 appearances for West Ham this season, scoring twice.
The 31-year-old began his career at Livingston before joining Leeds, then in League One, in the summer of 2008.
He spent four years at Elland Road, helping the club win promotion back to the Championship in 2010, before joining Norwich in the summer of 2012.
Snodgrass spent two seasons with the Canaries but left in the summer of 2014 following their relegation, joining Hull.
Two and a half years later Snodgrass joined West Ham from the Tigers in January 2017 for a fee in the region of £10.2 million (£13.3m).
After 15 appearances without a goal Snodgrass was told he could leave the club in the summer of 2017, eventually joining Aston Villa on a season-long loan.
He scored seven goals and provided a further 14 assists for Villa, helping the Midlands club reach the play-off final at Wembley, where they were beaten 1-0 by Fulham.
After returning to West Ham last summer, Snodgrass was given another chance to prove himself under new manager Manuel Pellegrini.
The London club are currently 11th in the Premier League with four games remaining.
They have an outside chance of qualifying for Europe, with a five-point gap between themselves and seventh-placed Leicester. Next up for West Ham is a game against the Foxes at the London Stadium on Saturday.
Whoever finishes seventh will earn a place in the Europa League qualifiers in July, provided Manchester City beat Watford in the FA Cup final at Wembley next month.