A tension headache (renamed a tension-type headache by the International Headache Society in 1988) is the most common type of primary headache. The pain can radiate from the lower back of the head, the neck, eyes, or other muscle groups in the body. Tension-type headaches account for nearly 90% of all headaches. A number of medications have been found to be useful for prevention, including tricyclic antidepressants and SSRIs. Evidence is poor for propranolol and muscle relaxants. Tension headaches affect about 1.4 billion people (20.8% of the population) and are more common in women than men (23% to 18% respectively).