Both aspirin and paracetamol (also referred to as acetaminophen) have been used to treat headaches since the end of the 19th century and while they are both essentially analgesics (pain killers) there are some very important differences between these two drugs.



Aspirin works by binding to and blocking an enzyme which is necessary for the production of a group of natural body hormones known as prostaglandins. These body biochemicals come into play whenever you suffer inflammation, such as that which occurs whenever body tissue is injured.

If you catch your finger in a drawer while you are closing it the damage to the tissue of your finger will begin the production of prostaglandins at the site of the injury and these prostaglandins will send signals along the nerves from the finger to the brain which you perceive as pain. At the same time it also provides the stimulus which will cause your finger to swell and, in this case, swelling is simply the body's reaction to the increased flow of blood into the area surrounding the injury. By interfering with the production of prostaglandins aspirin both reduces the pain felt and also the degree of swelling.

Unlike aspirin, paracetamol does not act as an anti-inflammatory and does not block the effects of the enzyme necessary for the production of prostaglandins, but it does inhibit this enzyme. In other words, it acts to block the pain but not to reduce the swelling.

There are several advantages to using paracetamol not the least of which is that it does not weaken the lining of the stomach or carry the risk of kidney damage, both of which are risks with the prolonged use of aspirin. In addition, it does not interfere with blood clotting as does aspirin and so is safer in the event of sustaining a cut or for people who are prone to nose bleeds. Paracetamol can also be taken safely by people suffering from certain diseases, such as Reye's syndrome, where the use of aspirin is considered to be unsafe.

As with most drugs there are of course risks with paracetamol and these are seen particularly when it is taken in improper or high dosages. For example, taking paracetamol on a regular daily basis can result in what are known as rebound headaches and, at high enough dosages, paracetamol can lead to liver damage and ultimately to death. These risks are of course low, but they can be increased substantially by, for example, taking paracetamol in conjunction with alcohol.

Some of the signs to watch for in the overuse of paracetamol are tarry, black or bloody stools, a skin rash and a sore throat. Very occasionally overuse will also result in lip ulcers or in white spots inside the mouth.

Whether you should reach for the aspirin or a paracetamol tablet to cure your headache is something of a matter of personal choice and for most people who suffer only occasional headaches it probably does not matter, unless other conditions would make you susceptible to the risk of side effects from one or other of these two drugs. If you find however that you are having to reach for either too frequently then you should consult your physician to discuss the best course of action for curing your headaches.