Is Analgesic Rebound Headache a Myth?

September 27, 2017

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Medication overuse headache (MOH), also known as rebound headache or drug-induced headache, may be the stuff of legend.  The evidence for it is sketchy.  The authors say, “Until the evidence is better, we should avoid dogmatism about the use of symptomatic medication.”

Why does this matter?
We often recommend patients avoid over-the-counter analgesics when having recurrent headaches because the dogma is that frequent analgesic use and withdrawal causes rebound headaches.  This may be true in rare instances, but it is likely less common than previously thought.  The authors argue there may be harm; stopping an analgesic may do nothing to help the patient and may deprive them of at least some headache relief.

Catch you on the rebound
The authors in this Viewpoint note that the evidence base for MOH is very weak.  Most is based on observational data that suffers from confounding by indication.  This means that people may use more analgesics because they have more frequent and more severe headaches, not the other way around.  Of course analgesic use correlates with headache frequency, but does that make analgesic use causative?  They do an excellent thought experiment by comparing headache to poorly controlled asthma, asking, “Is not the more plausible interpretation simply that medication overuse is an indicator of poorly controlled asthma, not a cause of it?”  Would we blame albuterol in a poorly controlled asthmatic requiring frequent albuterol or would we not say this indicates a more severe case of asthma?  The authors also note that in 2 RCTs with patients taking daily aspirin (ASA) that migraineurs assigned to the ASA group had improvement in headache compared to those who received placebo.  And they note:
“A guideline issued in 2012 by the American Academy of Neurology and the American Headache Society concluded that several non-steroidal anti-inflammatory drugs, including ibuprofen, naproxen, and ketoprofen, are ‘probably effective and should be considered for migraine prevention.’ It is difficult to reconcile this evidence with the widespread belief that regular use of these medications worsens headache.”
One would also think “analgesic detox,” would help, but it was successful in less than 1/3 of patients in 5 out of 6 studies that evaluated this outcome.  There were no controls, so this improvement may be explained by natural history or regression to the mean.  Maybe MOH is real, but the current evidence base for it is very flimsy.

Source
Medication overuse headache: An entrenched idea in need of scrutiny.  Neurology. 2017 Aug 18. pii: 10.1212/WNL.0000000000004371. doi: 10.1212/WNL.0000000000004371. [Epub ahead of print]

Peer reviewed by Thomas Davis, MD.