It depends! If it's too much unhandled stress, that negatively affects your health overall, including your skin.
Stress is a normal part of life. Stress triggers certain physical responses that prepare your body "to run for its life" - which is okay on a short-term basis but not constantly. The hormones that are triggered by stress are actually destructive over an extended period of time, and so you get health problems if you have too much unmanaged stress.
For a great definition of stress, check out
http://www.improving-health-and-energy.com/stress-affect-lifestyle.html
Cheers,
BB