Brown, who is leaving for Newcastle at the end of the season, was sent off for the first time and handed a six-week ban for stamping on Tommy Taylor’s head in Quins’ victory over Wasps earlier this month.
Brown appealed the verdict at a hearing with a fresh independent disciplinary panel on Wednesday night, but saw it rejected.
A statement read: “The appeal was dismissed.
“The Appeal Panel did not accept the submissions that the Disciplinary Panel had come to a decision to which no reasonable body could have come, particularly bearing in mind that the burden is on the player to establish on the balance of probabilities that no reasonable Disciplinary Panel could have come to the same conclusion.
“The original sanction stands.”
A shortening of the ban might have seen Brown available for the Premiership’s knockout phase, if Quins – who are fourth, 11 points clear of Northampton Saints – make it.