When triggers such as stress or muscle tension stimulate pain-sensitive nerves in the head, face, mouth, or neck, headaches can occur. Headaches are so common that they affect up to 95 percent of women and 90 percent of men at least once during their lifetimes. Although most headaches do not require medical attention, headaches that are more serious may indicate an underlying condition. Be sure to contact your healthcare provider if you have a fever or convulsions along with your headache or if you have a headache following a blow to the head.