Table 1

International Headache Society Classification criteria for frequent episodic and chronic tension-type headache5

Frequent episodic tension-type headacheChronic tension-type headache
A. At least 10 episodes of headache occurring on 1–14 days per month on average for>3 months (≥12 and <180 days per year) and fulfilling criteria B–D A. Headache occurring on ≥15 days per month on average for>3 months (≥180 days per year) and fulfilling criteria B–D
B. Lasting from 30 min to 7 days B. Lasting hours to days, or unremitting
C. At least two of the following four characteristics:
1. bilateral location
2. pressing or tightening quality
(non-pulsating)
3. mild or moderate intensity
4. not aggravated by routine physical activity such as walking or climbing stairs		 C. At least two of the following four characteristics:
1. bilateral location
2. pressing or tightening quality
(non-pulsating)
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
2. no more than one of photophobia or phonophobia		 D. Both of the following:
1. no more than one of photophobia, phonophobia or mild nausea
2. neither moderate or severe nausea nor vomiting