During a migraine or cluster headache, blood flow may be reduced causing symptoms such as flashing light, nausea, and unilateral facial weakness, and debilitation.

Dilation of the blood vessels then cause pain and local tissue swelling.

HBOT may abort a headache in progress or may increase the time interval between headaches. This is due to decreasing swelling, oxygenating the brain, and breaking the cycle of blood vessel spasm and dilation.