Cefaleia por uso excessivo de medicação

What is medication-overuse headache?

Medication-overuse headache (medication-induced headache) is a type of headache that is caused by using headache-relief medications (pain relievers or triptans) too often.

The only effective treatment is to stop the medication that is causing it. This often causes headaches or migraines to get worse for a short time, before improving afterwards.

Medication-overuse headache (medication-induced headache) is the third most common cause of headache after migraine and tension headache. The correct medical term for it is 'medication-overuse headache' even though you may only be taking the medication at the recommended dose.

• Quem desenvolve? Medication-overuse headache happens in people who are using headache-relief medicines a lot. It happens in people who already get other types of headaches, such as migraines or tension headaches. About 1 person in 50 develops this problem at some time in their life. It can happen at any age but is most common in people in their 30s and 40s. It is more common in women than in men.

• Causes: Medication-overuse headache is caused by taking painkillers or triptan medicines too regularly for tension headaches or migraine attacks. It can happen when you have been taking the medication as instructed. It is a common cause of headaches that happen daily, or on most days. Some patients feel that their headache never leaves them at all.

• Diagnosis: The diagnosis of medication-overuse headache is very important as, when overusing medication in this way, other treatments (such as headache preventers) are unlikely to work.

• Sintomas: Medication-overuse headache is defined in the following way:

  • It affects people who have had a previous diagnosis of headache problems.

  • You have headaches on at least 15 days per month.

  • Your symptoms are not more suggestive of another cause.

  • You have been using medications for treatment of the symptoms of headache regularly for at least three months at a high or frequent dose.

The headaches must resolve - or your headaches must go back to the pattern of pain you had before the problem started - within two months of stopping overuse if the diagnosis is to be definite. Until then, your diagnosis will be 'probable medication-overuse headache'. It is only after you are better that you and your doctor can be absolutely certain.

Some medicines are more likely than others to cause medication-overuse headaches. The risk of developing medication-overuse headache is much more closely linked to taking these medicines regularly over a long period - at least three months - than to the dose you take over a shorter period.

Bunching up of days of treatment with long gaps in between is much less likely to cause the problem. That means this problem is more likely if you overuse the treatment both frequently AND regularly, ie on two days or more per week.

If you take any of these medicines on at least 10 days a month for at least three months, you are at risk of medication-overuse headache:

• Opiate-containing medications such as codeine tend to cause problems most frequently. Codeine, both on its own and in co-codamol (combined with paracetamol), are probably the worst culprits.

• Triptans used for migraine attacks, such as almotriptan, eletriptan, naratriptan, rizatriptan, sumatriptan, and zolmitriptan. (Strictly speaking, triptans are not classed as painkillers. They work in a different way. However, they can cause medication-overuse headache.)

• Ergotamine (although this is now rarely used).

While other painkillers are less likely to cause medication-overuse headache, they can still trigger it if you take them on at least 15 days a month. These include:

• Anti-inflamatórios não esteroides (AINEs). These include ibuprofen, aspirin, naproxen and diclofenac.

• Paracetamol.

Medication-overuse headache may, however, develop in some people who take less than this. This is why the general advice is that you should not take painkillers or triptans for headache or migraine for more than a couple of days at a time. Also, on average, you should not take them for more than two days in any week for headaches or migraine.

The amount and frequency of medication use needed to cause medication-overuse headache is not clear. It varies between different people. It is possible that some people have more sensitive 'headache sensors' than others.

A typical case

1. You may have a bad spell of tension headaches or migraine attacks, perhaps during a time of stress. You take painkillers or triptan medicines more often than usual. You continue doing this for a while. Therefore, your body becomes used to the painkillers or triptan.

2. A rebound or withdrawal headache then develops if you do not take a painkiller or triptan within a day or so of the last dose. You think this is just another tension headache or migraine attack, and so you take a further dose of painkiller or triptan. When the effect of each dose has worn off, a further withdrawal headache develops, and so on.

3. A vicious circle develops. In time, you may have headaches or migraine attacks on most days, or on every day. You then end up taking painkillers or a triptan every day, or on most days. Some people start to take painkillers or triptans routinely every day to try to prevent headaches or migraine attacks. This only makes things worse.

The headache of medication-overuse headache is often described as oppressive and tends to be worse first thing in the morning, or after exercise. It may be a constant dull headache with spells when it gets worse.

Medication-overuse headache is much less likely to develop if you take painkillers regularly for other painful conditions such as arthritis. It usually only happens if you take painkillers or triptans for headaches or migraine. We don't know exactly why this is the case. It may be because people who are already prone to frequent migraine attacks or headaches are the same people who are more prone to having medication-overuse headache.

However, if you are already prone to headaches, you may develop medication-overuse headache if you are taking regular painkillers, even if you aren't originally taking them for headache. This may relate to the sensitivity of your headache 'pain sensors'. If these are already extra-sensitive, they may then be more prone to be stimulated by medication to become more sensitive still.

The most important part of treatment is to recognise and understand the cause of your frequent headaches - the painkillers or triptans.

• Plan to stop. You can then devise a plan to stop the painkillers. This is best done with the advice of a doctor. it's best to plan a day to stop them altogether rather than try to cut down gradually. You should stop taking them for at least one month, and possibly two. If you're taking opiate-based painkillers, you're likely to need extra support.

• Withdrawal symptoms. You must stop the painkillers or triptan completely to cure the problem. Do not take an alternative painkiller unless advised by a doctor (see below). This is an uncomfortable process. You are likely to experience withdrawal symptoms - particularly an initial worsening of headache, but also some or all of:

  • Enjoo (náusea).

  • Mau sono.

  • Inquietação.

  • Tummy upset or diarrhoea.

  • Ansiedade.

These symptoms are more likely when withdrawing from opiates and may last several weeks. Your doctor may want to discuss your case with a hospital specialist, and may refer you to them for help with withdrawal.

• Ask for support. Getting through this period of withdrawal involves willpower and commitment. It should help to understand that the complete withdrawal from medication is temporary, and is the first step in treatment, not the last.

• Preventative treatment for headache. Once the medication-overuse headache has ceased then regular, preventative treatment for headache may be started. In some cases, your doctor may recommend starting a low dose of preventative medication before the medication-overuse headache has completely settled, increasing the dose in the longer term.

• Measures to try. Other measures which can help during this period include:

  • Keeping your (non-alcoholic) fluid intake up, to ensure you stay well hydrated.

  • Keeping a diary of your symptoms (and, if your doctor has advised any other medication, any medicines you do take).

  • Trying to avoid taking on too many other commitments for at least a couple of weeks (and ideally a month) after you first stop the medication.

  • Considering some exercícios de relaxamento.

  • Trying to keep stress to a minimum.

• Switching medicines. Sometimes, although only under medical advice, switching medicines may be recommended. A medicine which carries a high risk of causing the problem (for example, codeine, which is more likely to cause medication-overuse headache) is replaced by one with a lower risk (such as ibuprofen).

• Withdrawal management. When you stop the painkillers or triptan, the headaches or migraine attacks are likely to become worse for a while. You will have to tolerate the headaches or migraine attacks for a while, and other withdrawal symptoms if they develop. Your headaches or migraine attacks should then gradually go back to a normal pattern. This often takes a week or two. However, in some people it can take a few weeks (occasionally up to 12 weeks) for the withdrawal symptoms to go completely and for headaches or migraine attacks to return to their normal pattern. This is more likely if your headaches are caused by opiate-based medication.

• A short course of an anti-inflammatory painkiller. If an anti-inflammatory painkiller is not the cause of the medication headache then your doctor may advise a short course of an anti-inflammatory painkiller. This may ease headaches after stopping the painkiller that caused them in the first place. This may sound illogical, but anti-inflammatory painkillers are in a different class of medicines to other types of painkiller. So, it may be an option to use one as a treatment in some cases if your body is not used to anti-inflammatory painkillers.

Your doctor may also prescribe an medicamento contra enjoo if nausea develops as one of the withdrawal symptoms.

In short - you will have to accept that things are likely to get worse, typically for a week or two, before they get better.

You can restart using painkillers or triptans as required when the pattern of your headaches or migraine attacks returns to normal. To prevent a recurrence of medication-overuse headache, as a general rule:

• If you develop a headache or migraine attack, it is OK to take two or three doses over a day or so. However, you should not take painkillers or triptans for headache or migraine attacks on more than two days in any week.

• Consider using preventative (prophylactic) treatment to stop the headaches or migraine attacks.

• Codeine and tablets containing codeine, such as co-codamol, are best avoided altogether. They are more likely than other painkillers to cause medication-overuse headache.

• You might have to decide not to treat some headaches or migraine attacks. You may just have to wait for them to go if you have already used up the recommended quota of painkillers or triptans in the previous few days.

See a doctor if frequent headaches do not go, or if they return again in the future.

Dr. Mary Lowth é autora ou a autora original deste folheto.