Diagnostic criteria:
  1. Headache fulfilling criteria for 8.2 Medication-overuse headache
  2. Both of the following:
    1. regular intake of any combination of ergotamine, triptans, non-opioid analgesics and/or opioids on ≥10 days/month for >3 months
    2. the identity, quantity and/or pattern of use or overuse of these classes of drug cannot be reliably established.

Patients who are clearly overusing multiple medications for acute or symptomatic treatment of headache, but cannot give an accurate account of what, when or how much, are encountered not uncommonly. While a prospective diary record over several weeks might provide the information, it would also delay withdrawal which is clearly required.