Supermodel Moss, 31, completed a 30-day treatment at the Meadows Clinic in October (05), following the publication of pictures appearing to show her snorting cocaine in a UK newspaper.
Babyshambles frontman Doherty was dumped by Moss this week (begs28NOV05) when he failed to complete a similar rehab programme at the same clinic.
And Doherty, 26, who was arrested in London yesterday (30NOV05) on suspicion of possessing crack cocaine, also believes Moss is frightened of being drawn back to drugs.
He says, "Everyone believes she went in there to beat her cocaine addiction. That's wrong. She did it to save her career.
"Having said that, she came out saying it really works.
"But she is terrified of her will-power failing. She's petrified of being caught again. She knows if she ever went back to drugs she would have to be more discreet."