By having others bite into her skin and suck out her chakra, Karin can heal other's wounds. This ability has been shown to heal even life threatening injuries in a short period of time, and is capable of quickly energising those Karin heals. However, this technique rapidly depletes her chakra reserves, and Karin is left with a permanent bite mark every time she uses it. Karin has many bite marks spread throughout her arms, chest, and neck, implicating that she has used this ability repeatedly in the past. Due to its depletion of chakra, it is dangerous for her to use this ability more than once a day.
Karin appears to become aroused when she is bitten, but as this was observed when she was healing Sasuke, it could merely be because it was Sasuke who was biting her.