Episodes resolve after minutes to hours but tend to become more frequent over time. If due to arthritis, pain is generally more pronounced after periods of inactivity. Seen with respiratory tract infections, gastroenteritis, and flu viruses. Is thought to be caused by generalized cranial vasodilatation. Hypertension generally does not cause pain unless significantly elevated.
Hypertensive crisis can cause very severe, generalized headache.
It is important for clinician to differentiate between headache caused by hypertension and hypertension caused by headache from another cause. Air pollutants, such as incense and perfumes, may also trigger primary headaches. Headaches associated with menstrual cycle, including those linked with oral contraceptives, may be caused by fluctuating levels of estrogen. Fluctuating hormone levels may also trigger primary headaches. Before considering this type of pain benign, clinician should rule out leaking aneurysm, increased intracranial pressure, and arterial dissection.