A headache is pain or discomfort in the head, scalp, or neck. Headaches are of various types like tension headaches, migraine, cluster headaches and sinus headaches.
Secondary headache is associated with an underlying condition such as cerebrovascular disease, head trauma, infection, tumor, and metabolic disorder (e.g., diabetes, thyroid disease). Head pain also can result from syndromes involving the eyes, ears, neck, teeth, or sinuses. In these cases, the underlying condition must be diagnosed and treated. Also, certain types of medication produce headache as a side effect. Most of headaches are caused by tension in the muscles of the neck and scalp after periods of stress and concentration. Eyestrain rarely produces headache (contrary to popular belief) and if it does it usually arises from astigmatism. Other causes range from sensitivity to certain foods like cheese, wines, changes in weather and altitudes, hormonal fluctuations, emotions, certain medicines (the oral contraceptive pill may also cause headaches, esp. during the pill-free week), smoking, alcoholism, as a forerunner of flu, after head injury, meningitis, etc.