Habib Ullah, 39, of Slough, Berkshire, was part of a group searched as they sat in a car in High Wycombe in 2008.
During the search he had breathing problems and later died in hospital.
An officer shouted "break his arm" as police tried to force a package of drugs out of his throat, the coroner heard. The inquest continues.
Emma Forbes, Mr Ullah's girlfriend who was with him at the time, told the inquest: "I could see by what was happening that it was a bit rough, the way so many of them jumped on him.
"I was hysterical, I was shouting, 'He's going blue, let go', and they were just ignoring me."
The search in Buckinghamshire on 3 July was carried out on the basis of police intelligence that Mr Ullah and his two friends had a stash of drugs in their car.
After carrying out an initial search of the three passengers and the vehicle, officers from Thames Valley Police noticed that Mr Ullah had a lump in his cheek.
Miss Forbes said: "They were saying to him, 'I know you've got something on you', and he was saying, 'No I haven't'.
"That's when one of the police officers said, 'You've got something in your mouth'.
"I remember the rest of them coming over, trying to restrain him, trying to put their fingers in his mouth, several of them trying to get his arms behind his back."
Miss Forbes told the coroner's court, sitting at Evreham Adult Education Centre in Iver, Buckinghamshire, that at one point there were five officers holding Mr Ullah face down on the ground.
She added: "Another two policemen had their hands around his throat, pressing down and putting their hands in his mouth at the same time.
"He couldn't speak because they had their hands around his throat, he couldn't say anything."
When it became clear that Mr Ullah was having problems breathing, police called an ambulance and he was taken to High Wycombe Hospital where he was pronounced dead.
A package of cocaine was found in his windpipe and another was retrieved from his colon.
The hearing, which is due to last eight days, continues.