Tension-type headache (TTH) is one of the most common (prevalent) forms of headache. The pain is typically felt on both sides of the head (bilateral) rather than just occurring on one side of the head and causes a sensation of pressing or tightening. The headaches are of mild to moderate intensity and are not aggravated by routine exercise such as walking. While tension headaches do not cause nausea, they may cause some sensitivity to light or sound. They last between 30 minutes to seven days. Frequent episodic TTH is categorised when a person experiences headaches between 1 to 14 days of every month.
Chronic tension-type headache (TTH) causes the same symptoms as episodic TTH (pressing/tightening sensation, mild to moderate intensity, possible sensitivity to light & sound), however it can also cause some mild nausea in addition to other symptoms. Chronic TTH is distinguished from an episodic disorder by headache frequency. Chronic TTH is when the person experiences headache on more than 15 days every month.