Physical Danger
You could charter a plane to a remote, dangerous location in a war zone and offer your services to poor villagers, but then you’d be in a Doctor’s Without Borders situation (link to Doctor’s without Borders career when up).
Odds are, you won’t be in much physical danger in this job. Most of the organizations that run these missions are very strict about entering hostile territory; still, there might be a stray crazy dictator lurking that they don’t know about. You could wander off and get lost in the jungles in Columbia and captured by a dictator-in-the-making who makes you his coffee bean picking slave. Also some US locations might involve going to Jersey.
You could catch Malaria, Cholera or Ebola if you’re going to the Africa in the middle of an epidemic and you forget your shots (though being a doctor, you should know better – serves you right, shame on you).
On a scale of 1-10 of danger, it’s not as safe as working from your office in Beverly Hills, but then again probably not as bad as driving to LAX at rush hour, or cruising on foot through the Gaza strip at sundown.