The Medication-Overuse Headache – a painful paradox

The medication-overuse headache (referred to hereafter as MOH) has been well-known for a relatively long time. It was first described as an independent phenomenon in 1951. According to its definition, the MOH is a so-called secondary headache. It is always connected to a primary headache disorder, usually migraine or tension-type headache, and develops through the overuse of painkillers. This overuse occurs when patients take pain medication on more than 10 days in a month and continue to do so over a period of more than three months. Around 90% of those affected have this kind of history with headaches; it practically never affects people with no pre-existing conditions, even when they take pain medication due to other symptoms.

An MOH is when the medication overuse described above triggers headaches on at least 15 days per month. The good news: MOH can be avoided by taking preventative measures and can be treated once it has set in. But more on this later.

How often does MOH occur?

Although the available data is relatively good due to numerous studies, estimates on the frequency of MOH differ. According to a study on the Global Burden of Disease, which is regularly published in the renowned medical journal ‘The Lancet’, around 1-2% of the general population are affected. This figure may seem low at first, but this means that between 50 and 100 million adults are suffering from MOH worldwide. According to the study, women are affected two to three times as much as men. Additionally, the illness seems to occur to a very different extent in different professional groups, meaning that we cannot reliably determine its actual impact from these averages. For example, sophisticated studies suggest that this problem is significantly more widespread in healthcare and nursing. Moreover, we must assume that there are a certain number of unreported cases in this context.

How does MOH develop?

The connection between the frequent intake of headache medication and the development of MOH is scientifically well-substantiated. However, the exact process of its development has not yet been sufficiently explained. Today, it is assumed that the body’s signalling and messenger substances which are responsible for the transmission and processing of pain stimuli have a role to play. Their function and mode of operation is altered through excessive medication intake. If this intake persists, pain control will be affected. Sensitivity to pain increases and headache attacks become more frequent and more severe. In this way, the medication is actually causing what it should have been preventing: excruciating headaches.

Effects on the brain

Through imaging techniques, it was demonstrated that there are changes in the condition of particular areas of the brain among patients affected by MOH. Scientists associate these with altered pain processing. Moreover, noticeable abnormalities were also found in the brain’s metabolism. For example, through PET scans (a high-resolution type of imaging), it was discovered that the number of available transport molecules for the important messenger substance dopamine was reduced in the areas of the brain which had been examined. From this, the scientists concluded that the brain’s signal transmission is affected by this shortage. This could be important in the development of MOH.

The observation that several of the identified changes reversed themselves, once the excessive medication intake had stopped, was of particular interest to researchers. However, this does not seem to be the case for all metabolic pathways which are affected by pain medication. For example, a disrupted glucose balance could not be returned to its normal level by ending medication intake. Intact, well-functioning glucose processing is therefore particularly crucial for preventing headaches.

Altered pain processing

According to newer studies, migraine attacks can alter the body’s pain processing system. In this context, this is also referred to as “conditioning”. With every new pain attack, a “pain memory” begins to form. The pain perception threshold is gradually lowered through this process. At the same time, the likelihood of an attack occurring increases. This leads to adjustment processes in the pain transmission circuits, at the end of which there is a so-called central pain sensitisation, and incoming pain signals are intensified. As a result, sensitivity is sometimes increased so much that signals which were initially harmless are perceived unusually intensely. The protective system which is responsible for pain modulation loses its ability to suppress pain occurrences so that they become harmless.

Messenger substances, which typically are also responsible for transmitting signals in the nervous system, are part of these processes. The changes which take place increase the likelihood of the dreaded wave-like activity in particular parts of the cerebral cortex (so-called ‘cortical spreading depression’, CSD), which scientists have long held responsible for the development of migraine attacks. This results in uncontrolled, “sustained fire” for the nerve cells.

Medication intake: always keep in mind the 10-20 rule

The most effective way of preventing an MOH is to keep to the so-called 10-20 rule. This states that painkillers can be taken on a maximum of 10 days per month, and that affected people should avoid taking this kind of medication altogether on at least 20 days per month. The amount and the dosage are irrelevant for this intake rule, as the number of “medication days” is what counts. The Headache Hurts app is especially helpful for this. It includes a medication tracker which warns users when their medication intake has reached a critical level. This can help you to follow the 10-20 rule.

What can be done to help?

However, if an MOH has developed, a medication break should be implemented as the most effective measure, accompanied by comprehensive medical support. Countless studies on this topic are unanimous in their recommendation, which can be summarised by the umbrella term “drug holidays”. In essence, the purpose of these is to remove the nervous system’s almost constant supply of painkillers and to refrain entirely from taking them for a specified period of time. Given that medication is what has originally caused the disruption of pain perception, its complete removal is seen as the only effective measure. Only by doing this do we give the pain regulatory system the chance to gain back control over pain occurrences. This sounds like classic drug withdrawal, and indeed works in a similar way. The central misalignment can be rectified in this way. As a result, the frequency and severity of attacks will go down, as could be demonstrated in numerous studies.

Sustainability requires support

Any withdrawal of this kind should be accompanied by behavioural measures if it is to be successful long-term. In addition, giving patients detailed information is an important foundation for preventing MOH. This can help them understand the fundamentals of the illness and creates an understanding of cause and effect with regards to pain occurrences. Many publications on this topic also emphasise the idea of ‘awareness’, i.e. knowing that pain medication can actually cause headaches.

A medication break can trigger a ‘rebound’ headache, which has a very negative impact on patients at first. This is why it is recommended to carry out this difficult phase with support from a doctor. For less severe cases, outpatient treatment can be sufficient, however, for more difficult episodes, current studies show that inpatient treatment is significantly more effective than treatment as an outpatient or in a day clinic.

Prevention over treatment

If you want to prevent the MOH, keeping to the 10-20 rule is the best method. If it is consistently followed, MOH can be avoided altogether. This leads to a noticeable improvement in quality of life, meaning that those affected have a strong motivation to stay committed long-term. It is well-documented that changing your behaviour to follow the 10-20 rule when taking painkillers has a positive effect on patients’ overall wellbeing for years to come. Equipped with this certainty, you have a good chance of successfully preventing and permanently overcoming the MOH.