"Taxi" star Jeff Conaway fights for his life!

VH1's "Celebrity Rehab with Dr. Drew" premieres January 10 -- and ET has an exclusive look at the inner world of Hollywood stars in rehab!

Tonight, we go inside JEFF CONAWAY's rehab emergency as the "Taxi" star finds himself in the fight for his life -- and an ambulance takes him to the hospital.

"His life was in danger," Dr. DREW PINSKY tells ET's JANN CARL. "His withdrawals were dangerous -- we tried to do it in a residential environment, but he got too sick. I had to put him in an acute medical facility for a few days."

Witnessing Jeff's trauma -- and working out their own addictions -- are fellow celebrities BRIGITTE NIELSEN, DANIEL BALDWIN, CRAZY TOWN musician SETH BINZER, JOANIE LAURER (the former wrestler known as Chyna) and former "American Idol" contestant JESSICA SIERRA.

"I know it's going to be an ongoing struggle [for Jeff]," says Dr. Drew. "Yeah, forever. Addiction is a chronic condition marked by relapses and Jeff, given the seriousness of his relapses, it's not just going to go away."

Watch ET for more of VH1's "Celebrity Rehab with Dr. Drew."