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September 21, 2025<\/p>\n
2 min read<\/p>\n
Nobody Knows How Tylenol Really Works<\/p>\n
The common pain reliever is safe when used as directed, research shows. But scientists remain puzzled by one aspect: how it reduces pain and fever<\/p>\n
By Josh Fischman edited by Jeanna Bryner<\/span><\/p>\n Tylenol is used by millions for pain relief.<\/p>\n Brendan Smialowski\/Stringer\/Getty Images<\/p>\n You\u2019re unlikely to open a medicine cabinet in the U.S. without seeing a bottle of Tylenol, the brand name of a pain reliever and fever reducer also sold generically as acetaminophen. A health care trade association estimates that 52 million consumers use a product containing acetaminophen every week in the U.S. The drug is in the news today after Robert F. Kennedy, Jr., head of the Department of Health and Human Services, implied that acetaminophen that is taken when a person is pregnant can cause autism in that person\u2019s offspring. His statements run counter to the most conclusive scientific evidence to date.<\/p>\n The drug is safe and effective when used as directed, but there is something surprising about it: no one is certain how acetaminophen works to relieve pain and fever.<\/p>\n There are at least two theories about the mechanism of the drug, which was first synthesized in the late 1800s. One is that the medication works by interfering with cyclooxygenase (COX) enzymes, which ultimately lead to the formation of prostaglandins, substances that can heighten pain sensations and drive inflammation and fever. By interfering with one of those COX enzymes, acetaminophen inhibits these prostaglandins from forming, says Steven Dudley, a clinical toxicologist and pharmacist, who directs the Arizona Poison and Drug Information Center at the University of Arizona. \u201cSo it\u2019s probably an indirect effect on prostaglandins,\u201d Dudley says.<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n The other idea is that the medication acts on body chemicals called endogenous cannabinoids, says Alex Straiker, a neuropharmacologist at Indiana University\u2019s Gill Institute for Neuroscience. Straiker has researched the mechanism and found that acetaminophen inhibited cannabinoid production in rodents and that this reduced their pain response.<\/p>\n \u201cPain pathways are very complicated,\u201d Straiker says. \u201cSo acetaminophen is likely to have multiple targets.\u201d It could affect both prostaglandins and cannabinoids, or it could act on other substances involved in pain perception, such as the neurotransmitter serotonin. Both he and Dudley say the medication\u2019s excellent performance may have reduced scientific interest in understanding the mechanism in order to improve it. \u201cThere could be no big incentive to figure out how it works,\u201d Straiker says.<\/p>\n If you enjoyed this article, I\u2019d like to ask for your support. Scientific American<\/span> has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.<\/p>\n I\u2019ve been a Scientific American<\/span> subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm <\/span>always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.<\/p>\n If you subscribe to Scientific American<\/span>, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.<\/p>\n In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.<\/p>\n There has never been a more important time for us to stand up and show why science matters. I hope you\u2019ll support us in that mission.<\/p>\n","protected":false},"excerpt":{"rendered":" September 21, 2025 2 min read Nobody Knows How Tylenol Really Works The common pain reliever is safe when used as directed, research shows. But scientists remain puzzled by one aspect: how it reduces pain and fever By Josh Fischman edited by Jeanna Bryner Tylenol is used by millions for pain relief. Brendan Smialowski\/Stringer\/Getty Images<\/p>\n","protected":false},"author":1,"featured_media":23215,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[50],"tags":[1244,629,14126,6321],"class_list":{"0":"post-23214","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-popular","9":"tag-safe","10":"tag-tylenol","11":"tag-works"},"_links":{"self":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/23214","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=23214"}],"version-history":[{"count":0,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/23214\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/media\/23215"}],"wp:attachment":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=23214"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=23214"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=23214"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}On supporting science journalism<\/h2>\n
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