It is often said in medical circles that, if aspirin was invented and launched these days, it would not get a product licence! There are so many troublesome side effects from it and some of them, such as a bleeding stomach ulcer, can be life-threatening.
Aspirin is an established medication because it was first on the scene and, despite its side effects, it works as an anti-inflammatory painkiller and as an effective treatment for fever. Back in 1899, when it was launched, there were very few synthetic medications available so people were prepared to take the rough with the smooth.
The effect on the stomach can cause a painful peptic ulcer which can erode into a stomach artery and lead to severe blood loss. The blood curdles in the acid environment of the stomach and emerges as substantial vomit which looks like coffee grounds – this is a serious situation. Even if the ulcer misses the artery, it can simply erode right through the stomach wall and produce a perforated ulcer which releases stomach contents into the abdomen and causes peritonitis which is even more painful and also life-threatening.
Bleeding is also generally aggravated by aspirin because it thins the blood by inhibiting platelet stickiness, an important component of normal blood clotting. It takes 80 days to replace a cohort of platelets completely so even one dose of aspirin, given in good faith for pain relief, can prejudice blood clotting for the best part of three months.
Other side effects include ringing in the ears and loss of hearing, severe allergy causing swelling of the eyes, face, lips, throat – similar to the allergic reaction seen with some foodstuffs or with insect stings – and some children develop a condition called Reye´s Syndrome which can lead to brain and liver damage and associated severe disability or death. The recognition of Reye´s Syndrome led to the end of the use of aspirin in children in the 1980s (under 16 years in the UK and under 19 years in US)) and, because it can affect babies in utero and also in breast milk, aspirin is not used in pregnancy either. Paracetamol became the first choice replacement, being very well tolerated and safe in normal dosage, and it has gone on to be one of the first choices for pain control and fever management as the children became adults in the decades following.
The pharmaceutical industry has applied much effort to produce alternatives to aspirin which is why there are so many anti-inflammatory medications on the market – the aim being to produce the most effective alternative but with the minimum of side effects and thereby corner a piece of this very big market. At the same time, aspirin could have gradually dropped down the list and gone into medical history, apart from the loyal adults with cast-iron stomachs who appreciate its effective painkilling temperature-lowering properties.
Paradoxically, the main reason aspirin has survived more generally as a first choice into the present time is its ability to thin the blood! This is normally a hazard and is more likely to be a problem when taken at painkilling doses but, when taken in a tiny daily dose, can be beneficial in preventing blood clotting that could lead to a heart attack or a stroke. The tiny dose is much less likely to cause the other side effects but is sufficient to reduce the platelet stickiness and preserve the person from blood clots seeding in a blood vessel and then dislodging to end up blocking an artery in the heart or the brain.
That could easily have been the end of the story but very interesting and important results are emerging which indicate that aspirin may have an inhibitory effect on the development of some common cancers.
In 2010, a retrospective analysis of research studies showed that individuals allocated aspirin for between four and eight years had about a 25% lower risk of dying from cancer. This protective effect continued long after the trials had ended. After 20 years, their overall risk of dying from cancer was still 20% lower than the placebo group.
More recent research is confirming this effect in the general population and seems particularly effective in preventing oesophageal, stomach and bowel cancers. The results for people at risk of hereditary bowel cancer are especially compelling but there are a string of studies confirming a positive effect in the general population. A very large study was reported in Philadelphia in April – after up to 32 years of follow-up, about 20,400 women and 7,570 men developed cancer, the investigators found, and men and women who took a regular dose of aspirin twice a week or more had a lower risk of cancer overall than people who did not regularly take aspirin. The reduced risk was again largely due to fewer cases of gastrointestinal cancers
It has been known for years that aspirin inhibits the production of prostaglandins, substances in the body that cause inflammation and pain. Prostaglandins also inhibit mechanisms that destroy cancer cells and therefore allow the cancer to start and to gain ground. Since aspirin reduces prostaglandin production generally, we may see a resurgence in the use of aspirin but now as a cancer preventer. The jury is still out and the authorities make cautious noises about not self-medicating because aspirin still has those potentially serious side effects outlined earlier. On the other hand, it is easy to see how people who are otherwise well and with no indigestion symptoms may decide to take a daily dose having decided that the benefits outweigh the risks.
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