Unsanitary conditions and overcrowding lead to rampant disease and infesations of pests (lice, rats). They were fed as little as possible and weren't given warmer clothes in the winter.
For some the torture went a little further. Some were made to transport the bodies of the recently killed to the crematorium (there's a movie about this). Some were forced to play in bands or orchestras that usually played at prisoner executions. Some endured solitary confinement. Some were forced into prostitution for camp guards. Some were subject to medical experimentation.
