Primary causes of severe headaches include migraines, trigeminal autonomic cephalalgia, and cluster headaches. Severe headaches are also secondary symptoms for serious conditions that require immediate medical care, such as a brain aneurysm, meningitis or concussion after an accident, according to Mayo Clinic.
Severe headaches due to chronic conditions normally do not require emergency care; however, pain that interferes with an individual's ability to work or sleep may require medical treatment, as suggested by Mayo Clinic. Even if a person suffers from chronic headaches, he may require immediate treatment if other symptoms accompany the pain, as stated by WebMD. These include partial loss of sight, inability to walk and loss of consciousness.