Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. A cluster headache is a pain that occurs along one side of the head; often around, behind or above the eye, and along the temple in a cyclic pattern of clusters. This is a very severe pain. Cluster headaches have no known causes neither triggering factors unless tension headaches or migraines. The dihydroergotamine nasal spray is used to narrow the blood vessels in the brain. This will cause the pain to come to an end. Unfortunately, its use is associated with side effects including gastrointestinal (thirsty, no appetite) and dizziness. Please report these side effects to the doctor who prescribed to change therapy. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Albana Sejdini