Tomar analgésicos pode realmente causar dores de cabeça?

More than 10 million people in the UK experience regular headaches, be those dores de cabeça tensionais (the most common kind), cluster headaches ou enxaqueca. Almost everyone has experienced a tension headache at some point, while around one in seven people are affected by migraine.

However, if your headache doesn't go away, it's worth investigating a counterintuitive possibility - that your headache is caused by the painkillers themselves. It is thought that 1-2% of the population (around one million Brits) suffer from 'medication-overuse headaches', in which the medication ends up creating the problem it's trying to cure.

"Medication overuse headaches are chronic headaches set off by the overuse of medication that treats headaches,” says Dr Farah Gilani, a GP at Medicspot. “They can also be triggered by taking painkillers for other reasons. Typically, for people who use the pain-relief medication more than two or three times a week, these headaches occur when the pain medication wears off and the headache comes back, leading the patient to take even more medication.”

It's a vicious cycle that can be hard to escape, not least because if you stop taking the painkillers altogether, your headache may initially get worse.

Who do they affect?

So how would you know it was a medication-overuse headache, as opposed to a headache plain and simple? Among people who deal with very regular headaches (more than 15 days a month), about metade meet the criteria for medication overuse, although it can be hard to know whether the overuse is the consequence or the cause.

Compounding the confusion, medication-overuse headaches generally only occur in people who are already headache-prone. You would be unlikely to develop this condition if headaches had never been a problem.

"People who are prone to medication overuse headaches are those who suffer from headache disorders such as migraine, cluster and tension-type headaches," says Gilani. "When they use medication on more than 10 days per month, this can lead to medication-overuse headaches."

One clue to look out for is that the headache is dull and constant. While migraine attacks are episodic, medication-overuse headaches are typically present every day and can be worse in the morning. Other symptoms can include difficulty concentrating, náusea, restlessness, memory problems and irritability. You may also notice that the headache has got worse since you began taking the medication.

"A dull throbbing in your head that occurs daily can be a sign of a medication-overuse headache," says Gilani. "If this pain goes away as soon as you take painkillers but returns when it wears off, you are likely suffering from medication-overuse headaches. These can occur in the same person, alongside other types of headaches such as migraine, and tension headaches."

The condition can be precipitated by a number of medications: aspirin, paracetamol, sleeping pills, anti-inflammatories like ibuprofen, codeine, prescription pain relievers, medicines containing caffeine, and migraine drugs called triptans.

According to NHS guidance, you could be at risk if you take aspirin, paracetamol or ibuprofen more than 15 days a month, or an opiate-based painkiller more than 10 days a month.

It's important to see your doctor as soon as you notice the characteristic pattern. Whether medication is the culprit or not, it's vital to get a proper diagnosis.

"If your headache is sudden or very severe, gets worse despite rest and pain medication, you usually have two or more headaches a week and take medication more than twice a week for headaches, you should consult your doctor," says Gilani.

If the GP suspects medication-overuse headache, they will work with you to help you come off the medication. While the withdrawal process does need to be individualised depending on the types of drug you're taking, most of the time you'll be advised to go cold turkey.

"The recommended course of action is to stop the use of painkillers and consult your doctor as they will know what treatment will best suit you," says Gilani. "Medications such as triptans and simple analgesics can generally be stopped abruptly. Other forms of therapy that can help include pharmacological and non-pharmacological therapy, biofeedback and targeted physical therapy."

Unfortunately, you may be in for an unpleasant few days. On top of a headache, you may experience withdrawal symptoms including nausea, sleep problems, diarreia, pressão arterial baixa, vomiting and ansiedade. Codeine-based painkillers can cause particularly severe side effects. Getting through this withdrawal period will require some willpower, and you'll want to time it judiciously.

"The withdrawal symptoms usually settle over a matter of days and the headaches should then have stopped," says Gilani. "If the headaches don't settle after stopping medication, an alternative diagnosis should be considered, and it is best to see your doctor to discuss this."

After the withdrawal is complete, you may wish to seek preventative treatment for the underlying headache disorder. While painkillers are a good way to treat occasional headaches, very frequent headaches may require a different strategy, so you don't return to this painful cycle.