What is a characteristic symptom of cluster headache?

Cluster headaches are known for their specific and intense characteristics. A hallmark of cluster headaches is unilateral retroorbital pain, meaning the pain is focused behind one eye. This pain is typically excruciating and can be described as sharp or burning. In addition to the intense pain, patients often experience other symptoms during an attack, such as lacrimation, nasal congestion, or miosis, all occurring on the same side as the headache.

This type of headache usually occurs in groups or "clusters," hence the name, and can follow a cyclical pattern, with individuals experiencing multiple headaches in a day for weeks or months, followed by periods of remission. The nature of the pain and its location are distinct and help differentiate cluster headaches from other types of headaches, such as tension-type headaches or migraines, which have different characteristics and symptoms.