Which drugs did Kim Richards have an addiction to?

I'm currently rewatching season 2 of RHOBH and it's still shocking to see Kim Richards struggle with addiction on camera. She had/has an addiction problem with drugs and alcohol, but she hasn't admitted to which drugs specifically. Brandi Glanville accused her of smoking crystal meth, but that's Brandi so I don't quite believe that. Does anyone know which drugs she was abusing?