Cluster headaches are very painful. They usually cause very strong pain on one side of the head, behind the eye and temple. The headaches can last anywhere from 15–180 minutes. People may have cluster headaches many times a day. Cluster headaches may also cause other symptoms. Most people get restless or agitated during an attack. Some people get a runny or stuffy nose. The eye on the side of the head that hurts can also get red or start tearing up. 