Sixty‐three headache patients (migraine: n = 28; tension‐type headache: n = 35) who fulfilled the IHS criteria of ‘drug abuse’ were investigated by means of the Minnesota Multiphasic Personality Inventory (MMPI) and the Critical Flicker Frequency (CFF) analysis. The results were compared to those of 63 headache patients without drug abuse (matched‐pair case‐control study).With respect to the MMPI results, no statistically significant differences between patients with drug abuse and patients without drug abuse were found. However, patients with drug abuse showed significantly decreased CFF values compared to patients without drug abuse. This was true both for patients with migraine and for patients with tension‐type headache.Thus, CFF analysis may serve as a useful method to differentiate between headache patients with drug abuse and those witho