Headache
A headache is a condition of mild to severe pain in the head; sometimes upper back or neck pain may also be interpreted as a headache.
Headaches have a wide variety of causes, ranging from eyestrain to inflammation of the sinus cavities to life-threatening conditions such as encephalitis. When the headache occurs in conjunction with a head injury the cause is usually quite evident; however, many causes of headaches are more elusive. The most common type of headache is a tension headache. Some people experience headaches when they are hungry or dehydrated.
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