<prompt> A cluster headache is characterized by all, exceptAffects predominantly femalesUnilateral headacheOnset typically in 20-50 years of lifeAssociated with conjunctival congestion  <response>: A cluster headache is a rare, primary headache 0.1The pain is deep, retro-orbital, excruciating, non-fluctuating, and explosive in quality.Unilateral pain for 8 to 10 weeks a year, followed by a pain-free intervalMen are affected three times more often than women.Patients with a cluster headache become aggressive during attacks.Parasympathetic autonomic activation: Ipsilateral symptoms of cranial conjunctival injection or lacrimation, rhinorrhea or nasal congestion, or cranial sympathetic dysfunction such as ptosis.The sympathetic deficit is due to injury to ascending sympathetic fibers surrounding a dilated carotid aery as it passes into the cranial cavity.Ref: Harrison; 19th edition 