No sex or nudity at all. The show focuses on the friendship of five doctors and their life in the hospital.
In S1 Ep1 towards the end of the episode, a doctor goes to the J International hotel and heads towards the elevator. When it opens, two people are shown kissing.
Violence & Gore
None
This is a medical show, so there are depictions of surgery that are occasionally mildly gory.
Alcohol, Drugs & Smoking
Mild
The main characters are shown sometimes drinking at a restaurant, or with their colleagues. A scene focuses on a patient who is addicted to narcotic drugs, and there is no other mention of drug use. Two of the main characters are implied to be smoking - we see them with the cigarette in their hand, but we do not see them actually smoking.