Most common are benign. Reasons can be illnesses that affect your body to local diseases such as sinus, or teeth. Most are not serious.
However, the most common cause is migraine. It can be treated with Ibuprofen, Naproxen or other medications. When taking these headache drugs, avoid products that contain caffeine. To prevent them, exercise regularly and get enough sleep!
If you've never suffered from headaches and has a severe headache with neck stiffness rather than just neck ache, meningitis is a consideration. You need to see a doctor asap.
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