India, April 12 -- Headaches are among the most common medical complaints worldwide, and a bugbear to many. From splitting or throbbing or dull disabling headache, to gripes that someone or a problem is a major headache, there are many grievances. Headaches are generally classified as primary, without an underlying illness, or as secondary, caused by an underlying condition like dehydration, infection, injury, vascular disease, or tumour, which needs urgent medical evaluation and management.Primary headaches like migraine, tension-type, and cluster headaches are usually benign, though disabling, and can be avoided through lifestyle changes, managed with standard treatments, or may need medical evaluation if they do not respond and persist...