What Causes Cluster Headaches?

Precisely what causes cluster headaches is unknown, but the condition has several well-recognized triggers, including alcohol, particularly if a person is going through a cluster period, and nitroglycerine or similar drugs. The fact that some of these triggers also cause blood vessels to dilate or open up to increase blood flow, or involve medications which make blood vessels constrict or narrow to reduce blood flow, suggests that changes in the vascular structure of the head may be partly responsible.

Triggers for cluster headaches include:

  • Alcohol
  • Smoking
  • High altitude
  • Bright lights and sunlight
  • Heat
  • Exertion
  • Nitrites in foods (e.g., processed meats)
  • Medications (e.g., nitroglycerin)
  • Illegal drugs (e.g., cocaine)

Other Headache Causes

Brain Tumors

Many people with brain tumors have headaches. Their pain may be worse in the morning as a result of pressure buildup in the brain after lying flat all night. It usually increases with coughing or straining, and is often accompanied by nausea and vomiting. CT (computer tomography) scans or MRI (magnetic resonance imaging) scans can help differentiate between cluster headaches and brain tumors.


Meningitis, an infection of the coverings of the brain, or brain abscess, a collection of infected tissue in the brain, also can lead to headaches. Such patients may have a stiff neck, fever, abnormal laboratory test or neurological examination results. CT scans, MRIs or a spinal tap, a procedure in which cerebrospinal spinal fluid is drawn for examination, may be necessary for a differential diagnosis.

Other infections that can cause headaches are sinusitis (sinus infection), ear infections, dental disease and infections of the eye.

Cerebral Aneurysm

An aneurysm is a widening of a blood vessel wall that can rupture, leading to bleeding in the brain, known as subarachnoid hemorrhage. The pain this causes has often been described as the worst headache of one's life. CT scans and MRI scans are used to make a differential diagnosis. Other tests include angiography (procedure in which a catheter is threaded upward through successive arteries to the neck and brain, where a contrast dye is injected into the blood to facilitate x-ray images) and spinal tap, which can disclose the presence of blood in the cerebrospinal spinal fluid.

Temporal Arteritis

An inflammation of an artery, this disorder usually occurs in older persons, and is associated with headache, muscular and joint aches, weight loss, malaise, fever and sometimes jaw pain. Its most worrisome symptom is transient visual loss, which may lead to permanent blindness if the disorder goes undiagnosed.

Patients typically complain of tenderness when the scalp or sides of the head are touched. Laboratory studies may show an elevation of the patient's ESR (erythrocyte sedimentation or "sed" rate), indicating inflammation. Some patients with temporal arteritis also have low blood iron levels (anemia). Most patients with suspected temporal arteritis are sent for a biopsy, in which a surgeon removes a small piece of the inflamed artery for microscopic examination to ensure correct diagnosis. Treatment involves steroids, mainly prednisone, often for an extended period to control the inflammation and prevent blindness.

Trigeminal Neuralgia

This pain, also known as tic douloureux, involves the nerves of the face and usually occurs on one side of the face only. Its pain is intermittent and severe, often describes as electric shock-like or stabbing. Talking, eating, or even by something as seemingly innocuous as wind blowing against the cheeks may trigger pain. Where many attacks occur in a short period, the face may be sore constantly. People often lose weight and sleep from frequent attacks.

Trigeminal neuralgia is most common in people over 40. The disorder may have many causes. Multiple sclerosis, tumors and blood vessel abnormalities may be responsible for a few cases, but in most instances the cause remains obscure.

One of the more commonly prescribed drugs used to treat trigeminal neuralgia is carbamazepine (Tegretol, Carbatrol). Three-quarters of all patients respond favorably to its use. Other medications that may be beneficial include gabapentin (Neurontin), tramadol (Ultram) and phenytoin (Dilantin). Pain medications also may be necessary during prolonged attacks.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Jan 2002

Last Modified: 18 Sep 2015