As others replied, anger is a very harmful emotion for your health, and holding it is not an adequate way to manage it as one should act on its sources (which can also be spiritual), if the sources of this anger are not managed the issue can get out of hand and become problematic. It can cause chronic fatigue and recurring body inflammation, as anger is martial energy, which when not in balance can cause general physical discomfort and various types of illnesses.
Behind an excessive manifestation of anger there is pain or deep suffering, which also applies from a spiritual point of view. Purify yourself consistently, free your soul from all the constraints on pain issues that are still part of your being. It is a long journey, during which you may encounter periods in which your anger worsens, but it is the way to remember, heal and affirm your desire to be free. To achieve the most short-term results, perform yoga, void meditation, breathing exercises, vibrate Runes of healing/feminine energy in your first chakra (no more than 9-18 if you are new in working with runes), choosing an affirmation aimed at managing or healing (the healing process however requires a path to long term) from the source of excessive anger.