Presence of following danger signals should warn a clinician that a headache may be more serious than migraine:

• Headache that is changing or different from previous headaches may herald a brain tumor superimposed on a longstanding primary headache disorder, such as migraine or tension-type headache.
• Headache with progressive worsening during 24 hours or several days suggest a mass lesion or infectious disease, such as meningitis, abscess, subdural or intracerebral hematoma, or vasculitis.
• Headache precipitated by exertion, bending over, coughing or sneezing may result from transient blockage of CSF flow or increased intracranial pressure.
• Sudden onset of headache during exercise or sex can occur with subarachnoid hemorrhage or could be benign exertional headache.
• Vomiting may result from a brain tumor or other mass lesion with increased intracranial pressure.
• Early morning headache can occur with obstructive sleep apnea and hypertension.
• Any abnormal physical or neurologic finding must be considered suspect, including fever, stiff neck, rash, lymphadenopathy, scalp tenderness, altered sensorium, and focal neurologic signs.
• Any patient who presents with their first or worst headache is cause for alarm (Blumenthal and Rapoport, 2001).