Analgesic Rebound Headaches Headache patients constitute one of the largest groups of patients in neurology outpatient clinics. Most of these patients have episodic primary headache disorders e.g. migraine, tension type headache, cluster headache etc. However, it is estimated that up to 4% of our population suffer from chronic daily headaches. In a recent study in Taiwan, transformed migraine was the most common subtype (55%), followed by chronic tension type headache (44%). Thirty-four per cent of these patients overused analgesics. This figure rises to 80% of patients with chronic daily headache who present to some American specialty headache clinics. A summary of 29 studies involving 2,612 patients with analgesic rebound headache revealed that migraine was the primary headache in 65% of patients, tension type headache in 27% and mixed or other headaches in 8%. The mean duration of daily headache was 5.9 years and an average of 4.9 analgesic medications were taken daily. Medication overuse can make headaches refractory to prophylactic medications. Although stopping the acute medication may result in withdrawal symptoms and a period of increased headaches, there is generally a subsequent headache improvement. In one study, most chronic daily headache patients withdrawn form frequent analgesic use and given no additional therapy eventually no longer had daily headaches; although 40% still had episodic migraine attacks. Apart from migraine and tension type headache patients, patients with hemicrania continua and new daily persistent headache are also at risk for overusing abortive medications due to their frequent headaches. However, it is not true that all patients with chronic daily headaches overuse analgesic medications. Some patients develop chronic migraine or chronic tension type headaches without overusing medications while there are others who continue to have daily headaches even after discontinuing frequent analgesic use. Medication overuse in headache patients is seldom due to primary substance abuse. It is also important to know that headache patients can develop a rebound phenomenon with daily headaches even if the analgesic use is for a nonheadache condition e.g. chronic low back pain. Apart from the risk of developing rebound headaches from frequent analgesic use; prolonged drug overuse has other serious consequences including hepatotoxicity, renal impairment and gastrointestinal ulceration. Tolerance to the analgesic, habituation and physical dependence may also occur. In addition, preventive or prophylactic medications are ineffective while a patient is in rebound. There are no studies quantifying the analgesic doses and duration of exposure needed to develop rebound headaches. Much of what we know derive from our observations and anecdotal data. Although they may be individual differences to the susceptibility of developing analgesic rebound headaches, certain guidelines have been suggested to limit this from happening. It is recommended that patients do not take simple analgesics more often than 5 days a week, triptans, combination analgesics or caffeine compounds not more than 3 days a week; and opioids and ergotamine not more than 2 days a week. At least 2 days a week, a patient should not take any analgesics even if they have chronic daily headache in order to avoid developing this rebound phenomena. At the NNI, we see headache and migraine patients at our weekly clinics at both the NNI-TTSH and NNI-SGH Campuses. Analgesic Recommended Use Paracetamol / NSAIDs No more than 5 days a week Combination Analgesics (Paracetamol/Aspirin + Caffeine/ophrenadrine) No more than 3 days a week Triptans No more than 3 days a week Opioids / Ergotamine No more than 2 days a week   References Lu SR, Fuh JL, Chen WT, Juang KD, Wang SJ. Chronic daily headache in Taipei, Taiwan: prevalence, follow-up and outcome predictors. Cephalalgia. 2001 Dec;21(10):980-6.  Rapoport AM. Analgesic rebound headache. Headache. 1988 Nov;28(10):662-5. Diener, H.C. and P. Tfelt-Hansen (1993). Headache associated with chronic use of substances. In The Headaches, pp. 721-727. Raven Press, New York. Bowdler I, Kilian J. The association between analgesic abuse and headache--coincidental or causal. Headache. 1988 Aug;28(7):494. Mathew NT, Kurman R, Perez F. Drug induced refractory headache--clinical features and management. Headache. 1990 Oct;30(10):634-8. Mathew NT. Drug-induced headache. Neurol Clin. 1990 Nov;8(4):903-12 Saper JR. Ergotamine dependency--a review. Headache. 1987 Sep;27(8):435-8