Cushing appealed the league's decision at a hearing at the NFL scouting combine in February but was informed Friday his appeal had been rejected, according to sources.
Cushing will be allowed to participate in training camp with the Texans this summer, but then will serve his four-game suspension to start the 2010 regular season.
"We were disappointed to learn that Brian has been suspended for the first four games of the 2010 season," Houston general manager Rick Smith said in a statement. "Brian is a productive member of our team and this is a significant loss, but we have to be prepared to win without him."
Cushing's attorney, Harvey Steinberg, did not return telephone calls seeking comment.
The Texans' defense will suffer without Cushing, especially considering that its first game of the season is against the defending AFC South champion Indianapolis Colts. Cushing will also miss games against the Washington Redskins, Dallas Cowboys and Oakland Raiders.
Cushing, who was voted to the Pro Bowl, had 133 tackles and helped lead the Texans to a 9-7 record, their first winning season in franchise history. Cushing finished the season with five sacks, four interceptions and two forced fumbles.
Cushing was hounded by rumors of performance-enhancing drug use before he became a pro, but the Texans were undeterred. They said then they found no truth to those rumors in their draft preparations.
"I've passed every drug test out there and still have," Cushing said during his 2009 draft news conference. "I'm not that kind of guy."
Cushing had been promoting an appearance on the NFL Network show "Total Access Live" scheduled for Friday evening on his Facebook page before posting the following message Friday afternoon: "Had to cancel NFL Network and all other interviews due to a family emergency. Heading to airport to fly back to NJ to be with the fam."
Cushing did not provide any further details about the emergency. He is from New Jersey and had been in school in California this week.
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