Paroxysmal hemicrania (PH) is defined by attacks of severe, unilateral headache, usually in the orbital, supraorbital or temporal region. These attacks are often associated with autonomic features, usually last less than 30 minutes and can occur multiple times a day.

PH sits within the group of disorders called trigeminal autonomic cephalgias which also contains cluster headache, a condition which shares many features with PH.

Importantly, PH is completely responsive to treatment with indomethacin.