Far worse are migraines and cluster headaches which can be completely debilitating.

BBC: Headaches and painkillers

Studies have found that most people who complain to their doctors about headaches have migraines -- as do nearly 90% of people who think they have sinus headaches.

CNN: Stop that splitting headache

Being aware may cause headaches now, but can prevent migraines in the future.

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Tension headaches can sometimes be difficult to distinguish from migraines, but unlike some forms of migraine, tension headache usually isn't associated with visual disturbances (blind spots or flashing lights), nausea, vomiting, abdominal pain, weakness or numbness on one side of the body, or slurred speech.

CNN: Tension headache

If you've had a history of migraines, for example, you could be denied coverage related to headaches, sinus infections and other vaguely related problems.

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