"Welcome to Dear Julia http a weekly column where readers can submit everyday health questions on anything from the science of hangovers to the mysteries of back pain. Julia Belluz will sift through the research and consult with experts in the field to figure out how science can help us live happier and healthier lives. Have a question Use our submission form httpsdocs.google.comformsdnBojnwSNqWYGlMzQcCOdoQdzaChMPOmNRRhKYtaviewform or ask juliaoftoronto httpstwitter.comjuliaoftoronto on Twitter. Whats the difference between Tylenol Advil and aspirin Which is the best to take for pain I used to take acetaminophen usually referred to by its brand name Tylenol for the occasional headache or sore muscle mostly because thats what we used in my house growing up. I didnt think much about whether it was more or less effective than any other type of overthecounter pain reliever and I suspect the same is true for many folks. Acetaminophen after all is the most popular httpard.bmj.comcontentearlyannrheumdis.full overthecounter painkiller worldwide. So I was surprised when I found out theres a huge gap between how pain researchers think about this drug and how the public does. More specifically every researcher I contacted for this piece said some variation of what Andrew Moore http a pain researcher at Oxford University told me Tylenol doesnt actually work that well for pain. To be more exact he said I cant imagine why anybody would take acetaminophen. Moore has done a number of systematic reviews on overthecounter pain medications looking at all the available evidence to figure out which ones work best for various problems. I asked him to describe the overall success rates for the most common three acetaminophen like Tylenol ibuprofen like Advil and aspirin. Like all good evidencebased medicine thinkers he was able to provide a very practical answer If youre talking about aspirin in doses of  to  mg or two tablets  percent of people get relief from acute pain. For acetaminophen at doses of  to  mg about  percent have a success. For ibuprofen in its normal formulation at something around  mg or two tablets about  percent have success. Now Moore was referring here to acute pain that strikes after a specific event like a surgery http_ibuprofenversusparacetamolacetaminophenforpainreliefaftersurgicalremovaloflowerwisdomteeth a cut or a burn but his message was simple Ibuprofen seems to work best followed by acetaminophen and then aspirin. For ongoing or chronic pain  a sore lower back say or the kind of degenerative arthritis that typically develops with age  ibuprofen still outperforms acetaminophen. WE FOUND THAT TYLENOL IS INEFFECTIVE ON BOTH PAIN AND DISABILITY OUTCOMES FOR LOW BACK PAIN A  systematic review http of highquality evidence published in the BMJ found that acetaminophen didnt seem to help most sufferers of chronic low back pain and that it barely alleviates pain in people with osteoarthritis. As the researchers wrote We found that acetaminophen is ineffective on both pain and disability outcomes for low back pain in the immediate and short term and is not clinically superior to placebo on both pain and disability outcomes for osteoarthritis. A limitation of the study is that the evidence on acetaminophen was mainly for acute low back pain but as the University of Leedss Philip Conaghan httplmbru.leeds.ac.ukpeopleourpeopleprofessorphilipconaghan explained There is very little longterm data on chronic back pain and if a drug doesnt work in the acute problem it seems unlikely to work in the chronic phase  though back pain may be even more complex than osteoarthritis pain. The study also noted that patients on acetaminophen are nearly four times more likely to have abnormal results on liver function tests compared with those taking oral placebo.  Other studies like this welldesigned randomized control trial httpard.bmj.comcontent.short of people with knee pain have similar conclusions Acetaminophen doesnt perform as well as ibuprofen and its linked to higher rates of liver problems. Ibuprofen also has potential side effects more on that below. So what about the occasional headache What works best for that It turns out this is another fascinating problem area for pain researchers. Moore has looked at all the evidence for what he calls infrequent tension headaches and found it is surprising how poor the research is and how little it tells us. Either the outcomes in studies are badly defined the studies have too few participants to say anything concrete or many people in the studies actually seem to have chronic headaches as opposed to the ordinary ones the researchers are allegedly studying. Most people would say if you look at the data take an ibuprofen http_oralibuprofenacutetreatmentepisodictensiontypeheadacheadults tablet Moore said. Acetaminophen is just not a very good analgesic pain reliever yet its the goto drug because its thought to be safe. And thats where things get even more interesting Acetaminophen isnt actually that safe. We always thought acetaminophen was safe but there are increasing signals of accidental overdose in people who are regularly using it for chronic pain and some liver toxicity explained Conaghan httplmbru.leeds.ac.ukpeopleourpeopleprofessorphilipconaghan who has studied adverse events data  httpard.bmj.comcontentearlyannrheumdis.fullrelated to this popular drug. Between  and  acetaminophen was the leading cause of acute liver failure http in the US. There are also hundreds of related deaths every year  though keep in mind that millions of people take drugs with acetaminophen so these more extreme side effects are rare especially if youre only taking them in small doses occasionally. Still for the drugs minimal painkilling benefits the risks may not be worth it.   Dont believe that just because something is overthecounter its safe Conaghan added. He advised people to see their doctor if theyre taking any of these painkillers for more than a few days  particularly if theyre on other drugs already. Tylenol is an old drug obsolete and should be avoided altogether  Kay Brune http a professor of pharmacology and toxicology at Germanys FriedrichAlexander University who has also studied the toxicity of painkillers was even more direct in his thoughts on acetaminophen Its an old drug obsolete and should be avoided altogether. Aspirin is safer than acetaminophen he said though to be used as a pain reliever it requires much higher doses  which can have side effects like stomach upset. Aspirin also interferes with blood coagulation for days after taking it. If you take one gram of aspirin Brune explained youre at risk of bleeding for another four days. This is why aspirin has its place as a protective agent against strokes and heart attacks for people at a higher risk. Ibuprofen doesnt have these two problems  its less toxic than the others in the doses that give people pain relief. But it has other side effects. Ibuprofen puts people at risk of bleeds in the gastrointestinal tract and kidney damage  so its not free of risk said Brune. Using it in high doses also seems to raise blood pressure and increase the risk of heart attack and stroke  one reason the Food and Drug Administration recently warned http_r people should only use ibuprofen and other nonsteroidal antiinflammatory drugs or NSAIDS like naproxen for short periods of time and in small amounts.  I asked Brune about what hed suggest for the occasional headache or sore muscle. Taking  mg of ibuprofen wont cause measurable harm he answered. Of all drugs we have available for most indications its also the most effective one. Is acetaminophen good for anything If the research community seems to have sided with ibuprofen for pain is acetaminophen good for anything  Yes. There are some groups of people with health complications who shouldnt take ibuprofen. For example patients with kidney gastric cardiovascular or bleeding problems may need to avoid NSAIDS like ibuprofen so doctors might suggest Tylenol in these cases.   Theres also some evidence that NSAIDS may increase the risk of psychosis and cognitive impairment in the elderly so doctors may avoid prescribing these drugs for older patients. And Tylenol is generally considered safer http than Advil or aspirin for pregnant women.  Fever is another area where acetaminophen can help said Moore. According to one systematic review http_paracetamolfortreatingfeverinchildren acetaminophen seems to be safe for treating very young kids with fever and you can give children http as young as  months old acetaminophen whereas you need to wait until kids are at least  months old to safely treat them with ibuprofen. This may help to explain the popularity of drugs like Tylenol for kids. But a final caveat here If your child is older than  months its not all that clear http that acetaminophen outperforms ibuprofen for reducing fevers and the same is true for adults. http So keep that in mind the next time you confront your medicine cabinet."