Red flags The following findings are of particular concern: Neurologic symptoms or signs (eg, altered mental status, weakness, diplopia, papilledema, focal neurologic deficits) Severe hypertension Immunosuppression or cancer Meningismus Onset of headache after age 50 Thunderclap headache (severe headache that peaks within a few seconds) Symptoms of giant cell arteritis (eg, visual disturbances, jaw claudication, fever, weight loss, temporal artery tenderness, proximal myalgias) Systemic symptoms (eg, fever, weight loss) Progressively worsening headache Red eye and halos around lights Interpretation of findings If similar headaches recur in patients who appear well and have a normal examination, the cause is rarely ominous.