Aspirin for severe headaches

“A jab made from liquid aspirin could be a powerful new treatment for migraine,” reported the Daily Mail. According to the newspaper, research has found that injections containing one gram of aspirin reduced pain in people hospitalised for headache.

This study reported the experience of researchers from a specialist neurological hospital where intravenous (IV) injection of aspirin was used to treat 168 people who were admitted with severe daily headaches. Most of these people’s headaches appeared to be related to overuse of other types of pain-relief medication. Treatment with IV aspirin was reported to reduce pain by those patients who kept a pain diary, although the study did not formally compare these patients to people who were not receiving the IV treatment. Also, only half the patients in the study kept a written pain diary, which prevents firm conclusions about the effectiveness of IV aspirin.

This study indicates that IV aspirin may show promise for the treatment of severe medication-overuse headache. However, to confirm these findings, it will take robust trials to formally compare IV aspirin to other drugs or no treatment. Even if this injected treatment is proven to be effective for this purpose, it is unlikely to be used outside hospital.

Where did the story come from?

The study was carried out by researchers from The National Hospital for Neurology and Neurosurgery in London and the University of California. No specific sources of funding for the study were reported.

The study was published in the peer-reviewed medical journal Neurology.

The Daily Mail’s headline – “Aspirin jab could beat your migraine misery” – implies that intravenous aspirin could be used for all migraines. However, the study only looked at treatment for headaches that were severe enough to require hospitalisation.

What kind of research was this?

This case series looked at the effects of intravenous (IV) aspirin on people hospitalised for severe headache. It took the form of an audit of the use of IV aspirin in a specialist neurological hospital in London. People are normally only referred to such specialist centres if doctors consider that they need expert assessment and management.

The researchers reported that in their experience and in previous studies IV aspirin had been found to be effective for treating acute migraine. Therefore, they wanted to assess whether it would be effective for chronic daily headache. In particular, they were interested in its effects in people who had severe headaches brought on by overuse of headache-relief medicines. These individuals are often withdrawing from medications such as paracetamol, opioids or triptans (used to treat migraine). These medicines cannot, therefore, be used to treat the withdrawal headache.

This type of study allows researchers at individual institutions to report their experience of using a particular treatment. It can be useful for determining how common side effects of treatments are. As there is no randomly assigned placebo control group, this type of study cannot demonstrate what would have happened if participants had not received IV aspirin.

The study also made an informal comparison between the patients’ pain after IV aspirin or chlorpromazine, a drug normally used to treat psychosis and severe agitation and sometimes the nausea and vomiting associated with cancer or opioid use. This comparison was not randomised and, therefore, cannot robustly tell us whether there are any differences in the effects of these treatments.

What did the research involve?

The researchers used pharmacy records to identify all people receiving IV aspirin for severe headache in their hospital between September 2001 and May 2006. They used patient diaries and medical records to assess the characteristics of these people and the effect of IV aspirin on their pain. The researchers also compared the use of IV aspirin with chlorpromazine in the subset of people who also received this drug during their hospitalisation, as a comparison.

The researchers identified 168 cases who had received IV aspirin and had case notes available. Pain was assessed using hour-by-hour diaries, which 86 patients had kept during their admission to hospital. These diaries recorded 652 doses of aspirin and 103 doses of chlorpromazine.

Pain was measured on a scale from 0 to 10, with a higher score representing greater pain. Pain was assessed during the three hours before aspirin or chlorpromazine was given, and for six hours afterwards. The pre-treatment pain score was taken to be the score at either one hour before treatment or at the time of treatment, whichever was higher. The post-treatment pain score was taken as the lowest pain score at one to three hours after the time of treatment. This approach was taken as the exact timings of the treatment and of recording the pain scores varied, and because the IV aspirin treatment aims to relieve short-term pain.

What were the basic results?

Of the 168 people receiving IV aspirin, about 70% were women and their ages ranged from 18 to 75. Most people (165 people or 98%) had chronic daily headache, defined as headache on 15 or more days a month over the past three months. About three-quarters had a primary diagnosis of migraine (77%). The majority had been overusing medication (159 people or 95%).

The patients were given 1g doses of aspirin intravenously, with half of the participants receiving fewer than five doses during their stay in hospital (patients were given between 1 and 50 doses). Chlorpromazine was used in 149 patients to give pain relief, reduce vomiting and for sedative effects at night.

Based on pain scores recorded in the patient diaries, IV aspirin reduced pain by one point on the ten-point scale on average (median), while chlorpromazine did not lead to a change in pain score on average. Intravenous aspirin:

  • reduced pain by one point, on average, in people with severe headache before treatment (pain score 8 to 10)
  • reduced pain by two points, on average, in people with moderate headache before treatment (pain score 4 to 7)
  • led to no reduction in pain, on average,  in people with mild headache before treatment (pain score 1 to 3)

Few people (5.8%) experienced side effects when using IV aspirin, and none of these side effects was serious. The most common side effect was nausea, which was thought to be related to the aspirin in four people. The second most common side effect was pain at the site of the aspirin injection into the vein, which was experienced by three people.

How did the researchers interpret the results?

The researchers concluded that IV aspirin is a safe and effective treatment for managing severe headaches in people admitted to hospital.


This study reported one hospital’s experience of using IV aspirin to treat people hospitalised for severe daily headache, mainly medication-withdrawal headache. This study gives some indication that the treatment can be safe and that people experienced some pain relief. However, there are a number of points to note:

  • The study was based on a retrospective review of medical records and patient diaries that were not designed specifically to assess the effects of IV aspirin. Information may be missing or may have been recorded in different ways in different cases, and this may affect reliability of the results.
  • About half the patients did not keep patient diaries (49%), and the experiences of those who did keep the diaries may have differed from those who did not.
  • Although an informal comparison with chlorpromazine was made, this comparison was not randomised and, therefore, cannot robustly tell us whether there are any differences between the treatments.
  • This was a study of people with chronic daily headache, mostly as a result of overuse of pain medication, who had been referred to a specialist hospital. Therefore, they cannot be considered as representative of the general population who experience headache and migraine. The results may not be indicative of what the effects would be in people with less severe headaches that do not require hospitalisation.

Randomised controlled trials would be needed to formally test the effectiveness of intravenous aspirin in people with medication-overuse headaches. If such trials show IV aspirin to be effective, it could be considered a useful alternative treatment in people with headaches caused by overuse of pain medications who cannot use the drug they are withdrawing from to control their pain.

NHS Attribution