I know someone who was hospitalized due to cocaine psychosis. This person had psychosis for three weeks even though he did not take any more cocaine in that time frame. It would have probably lasted longer if he wasn't given medications to treat it. They had to tie him up because he was extremely paranoid and thought that the doctors had kidnapped him and were planning to kill him.
Cocaine psychosis is more serious than people realize and it doesn't always last a few days.