Medication overuse headache

The current IHS headache classification does not differentiate exactly between substances which are responsible for the development of medication overuse headache although there are serious pharmacological differences between these substances. This fuzziness aggravates the comparison of clinical studies concerning medication overuse headache. This is special obvious for combination analgesics since the classification does not differentiate between combinations with psychotropic substances as opioids and such without psychotropic substances. A classification as supposed by Ferrari and colleagues which differentiates in substances with and without known psychotropic effects and different combination analgesics would be a step forward in order to be able to classify medication overuse headache better and to prevent misunderstandings.