Probable chronic tension-type headache

1. Headache occurring on ≥15 days per month on average for >3 months (≥180 days per year) and fulfilling criteria B-D
2. Headache lasts hours or may be continuous
3. Headache has at least two 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
4. Both of the following:
   1. no more than one of photophobia, phonophobia or mild nausea
   2. neither moderate or severe nausea nor vomiting
5. Not attributed to another disorder but there is, or has been within the last 2 months, medication overuse fulfilling the following: 1.Regular overuse for ≥3 months of one or more drugs that can be taken for acute and/or symptomatic treatment of headache, 2. Headache has developed or markedly worsened during medication overuse, 3. Headache resolves or reverts to its previous pattern within 2 months after discontinuation of overused medication