What is a trigger point? A trigger point is a knotted or tight area of muscle that can be felt under the skin and when pressure is applied, it often refers to either “triggers” or pain to another part of the body. A trigger point injection delivers a mixture of medications to reduce inflammation. The injection relaxes the muscle, which improves blood flow and promotes healing. Trigger point injections contain medication designed to break the pain cycle and successfully treat many muscle groups, especially those in the arms, legs, lower back and neck. In addition, they are often used for fibromyalgia and tension headaches.