A. At least 10 episodes occurring on <1 day/month on average (<12 days/year) and fulfilling criteria B-D

B. Headache lasting from 30 minutes to 7 days

C. Headache has at least 2 of the following characteristics:

1. Bilateral location

2. Pressing/tightening (non-pulsating) quality

3. Mild or moderate intensity

4. Not aggravated by routine physical activity such as walking or climbing stairs

D. Both of the following:

1. No nausea or vomiting (anorexia may occur)

2. No more than one of photophobia or phonophobia

E. Not attributed to another disorder

Frequent episodic tension-type headache

As "Infrequent episodic tension-type headache" except:

A. At least 10 episodes occurring on >/=1 but <15 days/month for ?3 months (>/=12 and <180 days/year) and fulfilling criteria B-D

Chronic tension-type headache

As "Infrequent episodic tension-type headache" except:

A. Headache occurring on >/=15 days/month on average for >3 months (>/=180 days/year) and fulfilling criteria B-D

B. Headache lasts hours or may be continuous

D. Both of the following:

1. No more than one of photophobia, phonophobia or mild nausea

2. Neither moderate or severe nausea nor vomiting