Suffering from back pain, headache, fever or cold? The pill of choice is usually paracetamol. The drug was introduced into the market in 1956, and GPs issue a staggering 22.9m prescriptions for paracetamol every year. So it’s disconcerting to read that it’s largely ineffective, according to a blog on Evidently Cochrane.

The solution

Cochrane is the international research group that adds up the evidence for treatments by combining results from high-quality studies, and it has looked at paracetamol quite thoroughly. Guidance from Nice recommends paracetamol as the first-line painkiller for low back pain. Yet Cochrane says that for acute back pain, 4g of paracetamol a day is no better than a placebo. It couldn’t find any good evidence that it worked for chronic backache.

For hip and knee pain from osteoarthritis, the drug provides such a small amount of pain relief that researchers wondered if it actually provided any benefit a person would notice.

If you’ve got a cold, paracetamol can help make your nose run less, but won’t help with sneezing, coughing, discomfort, tiredness or a sore throat. For migraines, it is is better than placebo but not as good as other painkillers. Meanwhile, if you have a tension headache, you have only a 10% chance of feeling better than if you’d taken a placebo. It can reduce fever in children – but Cochrane says the studies are poor and sponging down had a similar effect in the research it assessed. The drug does seem to reduce the pain from having your wisdom teeth extracted.

Paracetamol reduces the production of prostaglandins that are involved in inflammation, and so make nerve endings less sensitive to pain. How people break it down and how well it works for them is determined by genetics – it works better for some people than for others. It’s fairly safe, although rarely it can cause liver failure within the maximum standard dose (eight 500mg tablets a day).

Professor Phillip Conaghan, of the Leeds Institute of Rheumatic and Musculoskeletal Medicine and author of a paper on the safety of paracetamol, says we have been restricted to three types of pain killers for close to a century, one of which is paracetamol. The other two are non-steroidal anti-inflammatory drugs (which are associated with stomach ulcers and bleeding, kidney and liver damage) and opioids, which include codeine. The latter group causes constipation and a host of other side effects, and can also create dependency.

Conaghan adds that a painkiller may not always be the answer – for backache and osteoarthritis, strengthening muscles may work better than relying on painkillers. Headaches can often be prevented by looking away from screens, getting enough rest and avoiding dehydration. He thinks most people know that paracetamol isn’t great, although if it does work for you, keep taking it (but restrict your alcohol, as together they can damage your liver).