6. Headaches
A headache is something almost all of us has some experience with, and although they can be quite unpleasant and inconvenient, most of the time they are harmless and will go away on their own before too long. In other cases, it could be important to pay attention to a headache, especially if it starts happening more frequently than usual. Headaches can be the result of a serious infection, high blood pressure or stroke. Serious causes such as brain tumors and meningitis are less common but should not be overlooked.