Aspirin is back in the headlines again. This week, US researchers argued that the risk of bleeding from regularly taking aspirin cancels out the benefits of preventing heart disease once people turn 60. Experts from the Preventive Services Task Force, a US health body partnered with official government bodies, advise adults aged 60 and older against taking aspirin to prevent heart disease and stroke because of the “potentially serious harms” involved.

The research has added fuel to a debate that has been raging for some years on the pros and cons of whether to take aspirin regularly.  Low-dose (75mg daily) aspirin has historically been prescribed as a preventative treatment for heart attacks and strokes in at-risk individuals. The medicine can also be used as an everyday painkiller for ailments such as fevers and inflammation.

In recent years, researchers have suggested that taking the blood-thinning drug once a week can also cut the risk of developing certain cancers by nearly 40 per cent, and long-term aspirin use has been found to reduce the risk of developing several cancers. 

But many studies, including a major 2019 report from King’s College London, have found that taking regular aspirin can cause more harm than good. The drug has been shown to “substantially” increase the risk of serious bleeding for middle-aged and older people, and a 2017 Oxford University study suggested that taking a daily aspirin causes more than 3,000 deaths and around 20,000 bleeds annually.

With so much research out there, it’s easy to feel confused about whether or not you should be taking aspirin. Here’s everything you need to know.

What is aspirin, and what does it do?

Also known as acetylsalicylic acid, aspirin was first discovered in the late 19th century by German chemist Felix Hoffmann. The drug is used both as a pain reliever and preventative treatment for heart conditions, and remains one of the most commonly prescribed drugs in the UK.

“Aspirin is an antiplatelet drug,” explains Dr Claire Ashley, a GP based in Bristol. “Platelets are the components of the blood that make it clot, and aspirin thins the blood, making it less sticky and prone to clotting.” 

Blood clots can get lodged in the coronary arteries, affecting the heart’s blood supply (and blood clots blocking the flow of blood and oxygen to the brain leads to strokes).

“However, because you’re taking it orally, [aspirin] sits in the stomach and it can irritate the stomach and thin the lining,” explains Dr Ashley. “So you’re therefore at risk of developing ulcers and bleeding – stomach bleeds are particularly nasty for people to experience – and the evidence that’s come up now suggests that the risk of having a stomach bleed is greater than the preventative effect that it has on causing heart attacks and strokes.”

Is aspirin safe?

 In short, it’s complicated. “There’s been a lot of to-ing and fro-ing over the past 20 years about ‘should you take aspirin, shouldn’t you take aspirin’,” explains Dr Ed Pooley, a Nottingham-based GP. 

“What’s often difficult about aspirin is that there are two aspects to it. Primary prevention of disease (looked at in the context of heart attack and stroke risk) relates to your risk of developing those diseases if you haven’t had them before. Secondary prevention is when you’ve had cardiovascular disease and you’re at risk of having it again – in secondary prevention, almost everyone is in agreement that some form of anti-platelet treatment (so aspirin or a tablet called Clopidogrel) is a good thing to have because it reduces your risk.”

In primary prevention, however, recent studies have shown that aspirin risks causing kidney damage and bleeding and these risks are deemed greater than the benefits. So, if you’re otherwise fit and healthy, don’t take aspirin to reduce the risks of cardiovascular problems.

“It’s felt that for the majority of people, the risk of taking it and having an adverse event far outweighs the benefit of taking it and preventing heart attacks and strokes,” Dr Ashley says.

“There are ailments it is prescribed for, such as secondary prevention of heart attacks and strokes or to reduce the risk of pre-eclampsia for some pregnant women.”

And, although it has been shown to cut the risks of several cancers, aspirin is not currently recommended as a preventative drug for cancer. 

Should I take aspirin to reduce my risk of cardiovascular problems?

Take a safety-first approach, and consider your doctor’s advice and whether the benefits of taking daily aspirin outweigh the risks. “Unless you’ve been advised by your doctor, I would say not to – because of the risks. It’s not a completely safe drug without risks,” says Dr Pooley. 

“There are other things you can do that reduce your risk [of cardiovascular problems], which are probably safer – including eating a healthy diet, increasing your levels of omega three and six and fish oil in your diet,” he explains.

Dr Ashley agrees and emphasises that GPs have been advised against prescribing aspirin as a primary preventative drug. “We still prescribe it for some people who have had strokes and heart attacks – so that’s using it for secondary prevention – but for people who are at risk of heart attacks, we don’t typically prescribe it anymore.”

Can you buy aspirin over the counter?

Yes, you can buy over-the-counter aspirin, although it is unsuitable for those under 16. “For most things, aspirin over the counter is exactly the same as what we prescribe – and it’s very cheap, maybe £1 for a month’s supply,” Dr Pooley says. 

But he advises letting your GP know if you are taking over-the-counter aspirin so that they don’t prescribe you other medicines that can’t be taken at the same time.

Can you take aspirin when pregnant?

 Yes, you can. Low-dose aspirin is often prescribed to women at high risk of pregnancy issues, such as pre-eclampsia. 

What’s the difference between aspirin and other painkillers like paracetamol and ibuprofen?

“They’re all painkillers, but aspirin is an antiplatelet [and nonsteroidal anti-inflammatory] drug, whereas ibuprofen is a nonsteroidal anti-inflammatory drug,” explains Dr Ashley. “Ibuprofen affects the release of inflammatory messages between cells and prevents the release of chemicals that cause inflammation in the body. Paracetamol works on modifying pain messaging.”

“Aspirin and ibuprofen are very similar drugs, so you mustn’t take them together,” she says. “If you take them together, you’re at a much higher risk of a stomach bleed.”

While ibuprofen and aspirin are both nonsteroidal anti-inflammatory drugs, aspirin (with the common brand names Caprin, Disprin and Nu-Seals Resprin) is more likely to result in gastrointestinal problems. Ibuprofen is considered preferable for the treatment of ongoing conditions such as arthritis and menstrual cramps.

I’ve taken aspirin for decades. Should I stop taking it?

“The effect can be cumulative so, even though [individuals taking aspirin] might not have noticed a problem, they probably aren’t aware of things like their kidney function or things that require a blood test to monitor. In the absence of a clear reason, I’d say to stop taking it,” says Dr Pooley. 

However, if you have previously been prescribed aspirin as a secondary prevention for heart attacks and strokes, you mustn’t stop doing so suddenly as this would increase your risk of such cardiovascular problems. Let your GP know and ease off gradually.

“Some people do choose to stay on it and that’s fine,” says Dr Ashley. “That’s their decision, as long as they know that the advice has changed. When it comes to the prevention of strokes and heart attacks, we don’t recommend aspirin to prevent them.”

Instead, she explains: “We push lifestyle changes – for example, eating a diet that’s high in fruit and vegetables and unsaturated fats, and doing regular exercise. Doing 30 minutes a day, five days a week, is what the Government recommends as a minimum.

“And then it’s things like controlling your lipids, involving cholesterol-lowering drugs like statins… and controlling your blood pressure is really important in preventing heart attacks and strokes.”