Statins are the most prescribed drugs in the UK, with more than seven million people taking them every day. While the cholesterol-lowering tablets may reduce your risk of cardiovascular disease by a third if you've already suffered a heart attack or stroke, they're not without side effects.
See also: Statins 'may not cut heart attack risk in some patients'
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What are statins?
Cholesterol is one of the biggest risk factors for heart disease, stroke and disease of the arteries – the nation's biggest killer. Statins are taken to lower the level of low-density lipoprotein (LDL), or 'bad cholesterol', in the blood, thereby reducing the risk of cardiovascular disease.
The one-a-day tablets are commonly offered to people who have already been diagnosed with some kind of cardiovascular disease, including those who have suffered a heart attack, and those who are at high risk, typically with a one-in-five chance of developing a problem over the next decade.
Statins save lives
Statins reduce the risk of a fatal heart attack or stroke in high-risk users by a third, according to a review by the Medical Research Council in Oxford and the University of Sydney. In the UK, it's estimated that statins save around 7,000 lives each year.
So why the controversy?
Doctors have been prescribing statins since the 1980s to reduce the risk of cardiovascular disease.
However, the drugs have been the subject of controversy since NHS watchdog NICE recommended that anyone with a 10% chance of developing cardiovascular disease over the next 10 years should be offered the tablets (even if they do not have any symptoms of heart disease), making virtually everyone over the age of 40 eligible for the drugs.
Statins may be effective but they can cause a wide range of side effects – though the extent of these adverse effects is open to debate.
A recent major review in The Lancet said that statins are safe and their benefits far outweigh any harm, adding that their potential side-effects have been exaggerated by unreliable studies.
The Lancet review found that side-effects can include developing muscle pain, diabetes or a haemorrhagic stroke, but said that the suggestions that statins cause other conditions, such as memory loss, cataracts, kidney injury, liver disease, sleep disturbance, aggression or erectile dysfunction, are not accurate.
However, rival journal The BMJ challenged that claim by suggesting that the 'adverse' side effects are far more common than the Lancet study implied. Writing in a BMJ blog Richard Lehman said:
"Muscle pain and fatigability are not a figment of misattribution and public misinformation. They are too prevalent and recurrent in people who desperately want to stay on statins. Rather than discount a widely observed phenomenon, we should ask why there is such a mismatch with reporting in the trials."
Other side effects
In a Dutch survey of 4,738 statin users, 27% said they suffered from side effects, with 40% of those experiencing muscle pain and almost a third with joint pain. The poll also found that 16% had digestion problems, such as diarrhoea, and 13% described memory loss as a side effect.
The most commonly reported side effects include headache, nausea and insomnia, while between one in 100 and one in 1,000 people susceptible to inflammation of the liver, blurred vision and weakness. Severe side effects such as jaundice, nerve and muscle damage were rarer, affecting fewer than one in 1,000 people.
Worryingly, it's believed that as many as 200,000 people stopped taking the prescribed drugs over a six-month period because of fears over their safety. Health experts predict that around 2,000 people may suffer a cardiovascular event such as a heart attack or stroke as a result.
Oxford University's Professor Rory Collins, one of the authors of the review, said misleading claims about harmful side-effects was causing a "serious cost to public health".
He added: "Our review shows that the numbers of people who avoid heart attacks and strokes by taking statin therapy are very much larger than the numbers who have side-effects with it.
"In addition, whereas most of the side-effects can be reversed with no residual effects by stopping the statin, the effects of a heart attack or stroke not being prevented are irreversible and can be devastating."
Speak to your GP
Some GPs have said that there isn't enough evidence to suggest that wider usage of statins would benefit those in lower-risk categories. One US-based study found that 98% of people without a diagnosed heart condition who take statins for five years gained no benefit whatsoever, and only 1-2% would avoid a heart attack that might have occurred otherwise.
If you're not in a high risk category, it might be worth doing further research and talking to your doctor before deciding whether to take them.