What causes high liver enzymes?

My friend was recently caught mixing alcohol and prescription pills and literally almost died. I went to visit him today and he asked me a question that I was curious to know the answer to myself. His test results came up high liver enzymes. He is an alcoholic and everytime he goes t the hospital it is when its drunk. Does it automatically mean he has hepatitis? Or can his liver enzymes be high just from the drinking and then go back down? He will ask his doctor but hes known for not telling me the truth of test results because he doesnt want me to worry. Also is hepatitis always chronic? Can your immune system eventually get rid of it? Ive heard both sides.