Symptoms may include fever and headache, but the distinguishing characteristic of this disease is attacks of severe pain in the lower chest, often on one side.[3] The slightest movement of the rib cage causes a sharp increase of pain, which makes it very difficult to breathe, and an attack is therefore quite a frightening experience, although it generally passes off before any actual harm occurs. The attacks are unpredictable and strike "out of the blue" with a feeling like an iron grip around the rib cage. The colloquial names for the disease, such as 'The Devil's grip' (see also "other names" below) reflect this symptom.