Heal Bite

Karin heals other's wounds by having them bite into her skin and suck out her chakra. This technique rapidly depletes her chakra reserves, and Karin is left with a permanent bite mark every time she uses it, which she has 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 Karin to use this ability more than once a day.

Karin also appears to become aroused when she is bitten, but as this was observed when she was healing Sasuke, it could merely be the fact that it was Sasuke who was biting her.