Oxygen

Oxygen stops the pain in cluster headaches by inhibiting the trigeminovascular system, which is a network of nerves and blood vessels in the head. While the exact mechanism is not fully understood, other theories suggest oxygen can cause cerebral vasoconstriction (narrowing of blood vessels) and modulate neurotransmitters, which also helps to alleviate the pain. High-flow oxygen therapy is a cornerstone of acute cluster headache treatment because it works quickly to relieve the pain of severe attacks. 

How oxygen therapy works

  • Inhibits the trigeminovascular system: Oxygen may block the trigeminoautonomic reflex, a key pathway involved in cluster headaches.
  • Causes vasoconstriction: Inhaling pure oxygen can cause blood vessels in the brain to constrict, which helps to reduce pain.
  • Modulates neurotransmitters: The high oxygen levels may influence the levels of neurotransmitters in the brain, further helping to relieve pain.
  • Reduces inflammation: Oxygen may also reduce inflammation and damage to the blood-brain barrier, which are factors in headache pathogenesis.  [source]

Treatment protocol

  • High-flow oxygen therapy (100% O₂ via non-rebreather mask at 12–15 L/min for 15–20 minutes) is a cornerstone of acute cluster headache management. It is safe, fast-acting, and highly effective, often providing complete relief within 5–10 minutes when started promptly.

    Unlike medications, oxygen has no systemic side effects, can be used repeatedly, and is recommended as first-line treatment in all major clinical guidelines worldwide.
  • The rapid nature of cluster headaches means that treatments must work within minutes. Oxygen therapy is effective in this timeframe.
  • Some research suggests that the cooling effect from the inhaled oxygen may also play a role in relieving the pain, but this requires further study.  [source]

 Key safety notes

  • Always use a non-rebreather mask (not a nasal cannula or simple face mask).

  • Keep cylinders upright and stored safely away from heat.

  • Stop the flow once the attack resolves or after about 20 minutes.

  • If you need more than 3–4 sessions per day, discuss preventive treatments (e.g., verapamil or Emgality) with your neurologist.