Medicine treats injuries and diseases to support and speed healing. It treats distressing symptoms such as pain to relieve suffering during treatment, healing, and dying. The task of medicine is to relieve suffering under three circumstances. The first being when a painful injury or pathology is resistant to treatment and persists. The second is when pain persists after the injury or pathology has healed. Finally the third circumstance is when medical science cannot identify the cause of pain. Treatment approaches to chronic pain include pharmacological measures, such as analgesics, antidepressants and anticonvulsants, interventional procedures, physical therapy, physical exercise, application of ice or heat, and psychological measures, such as biofeedback and cognitive behavioral therapy.