BMJ Group Medical Reference
This information is for adults who get migraines. It tells you about aspirin, a treatment used for migraines. It is based on the best and most up-to-date research.
Does it work?
Yes. There is good evidence that your headache will feel better if you take aspirin alone or combined with an anti-emetic. (You can get aspirin with an anti-emetic only on prescription from your doctor).
Effervescent aspirin (the type you dissolve in water and then drink) taken alone or combined with the anti-emetic metoclopramide will also make you feel better. Taking aspirin in this way may work faster than taking tablets. That's because, as your migraine attack starts, your stomach and gut slow down. When this happens, it takes longer for tablets to be digested and get into your system.
What is it?
Aspirin is a popular painkiller. It is a type of nonsteroidal anti-inflammatory drug (NSAID).
You can take aspirin on its own or combined with paracetamol and caffeine. You can also take aspirin with drugs that stop you feeling sick (anti-emetics).
How can it help?
Aspirin can make your headache better, whether you take it on its own or combined with paracetamol or caffeine.  
Aspirin can make mild and moderate migraine attacks better, but it needs to be taken early on.
Aspirin can also reduce the pain of a more severe headache but may not get rid of it.
Aspirin, paracetamol, and caffeine taken together may help other symptoms, such as being extra-sensitive to light or noise. 
Aspirin works whichever way you take it. You can take it as tablets that you swallow with water, and as tablets that dissolve in water or in your mouth.   
One study found aspirin worked as well as a prescription drug called sumatriptan.  Another study found aspirin works as well as paracetamol combined with codeine. 
How does it work?
Aspirin is a painkiller. No one knows exactly how it works to relieve migraine attacks. But we do know that aspirin stops your body making chemicals called prostaglandins. Your body makes these chemicals when you are in pain or injured. They cause inflammation and make you more sensitive to pain.
By stopping the prostaglandins, aspirin may reduce the inflammation that causes migraines. Aspirin may also tell your brain to stop feeling so much pain. 
Caffeine, metoclopramide, and paracetamol can work with aspirin to help relieve the symptoms of migraine.
Caffeine causes blood vessels in your brain to narrow, and it may make aspirin work better as well.
Metoclopramide makes you feel less sick.
Paracetamol can help ease your pain.