It can make one look like a fool, lead to sin and also hurt one's health. On top of all that, it can only make a person's problems worse than he already thinks they are. A popular excuse for getting angry is righteous indignation - anger at sin. There are hundreds of scriptures which talk about the just fury, anger or wrath of Yahweh. Remember that Yahweh is the judge and that taking vengeance is reserved only for Him.
Pride is probably the most common reason for anger.
It results from the need to feel power over others or to control the situation or from the need to feel perfect. This kind of anger is based on a fear of inadequacy. If you feel this kind of anger you need to try to find where the self-doubt lies within you. Give up your pride and insecurity. Rely upon Yahweh for power that really means something.