Frequently Asked Questions about Acetaminophen
The 1950s introduced many things into our culture such as color TV, credit cards, seat belts, and Disneyland. Of all the wonderful or maybe not so wonderful introductions into this world during this decade, the most significant, in terms of treating chronic pain, was the introduction of Tylenol in 1955. This product was brought to market after the discovery that acetaminophen reduced pain and fevers with less toxic effects than its predecessors. Despite the prevalence and long-standing history of acetaminophen in our medicine cabinets, many people have questions about it.
What is it? What does it do? How does it work? Like all medications, acetaminophen is a chemical that interacts with the body in certain ways. Although, the exact way that it works is still being researched to this day, we know for certain that it reduces our ability to feel pain by its influence on the nervous system. It also reduces the body’s ability to produce higher temperatures, a fever. Since its discovery, acetaminophen has been the workhorse of the medicine cabinet when fever or pain strikes.
Can I use it with other medications? Acetaminophen is in its own class of medications; thus can be used with anti-inflammatory medications because it is not an anti-inflammatory medication. In fact, there are no serious, documented medication interactions with acetaminophen. (1) The problem with using it with other medications is that many other medications contain acetaminophen and dosages can accumulate rapidly. Taking too much of it in one day can be deadly toxic.
How much acetaminophen can I use? For years the highest recommend daily dosage of acetaminophen has been 4000mg per day. But recently the FDA suggested that the maximum daily dose be lowered to around 3000mg per day which prompted much confusion (2). Based on some recent research about safety, I advise a person that for regular use 3000mg per day is the maximum dose per day; however, for those with healthy livers, an occasional dose of 4000mg in a day is safe.
Is it safe? Because too much acetaminophen is toxic to the liver, researchers have been studying the effects of certain doses on the liver. In one study, 1000mg taken twice daily for 12 weeks had no clinically significant effect on the liver (3). In another study, there was no evidence of liver damage that occurred after recently abstinent alcoholics used 3000mg of acetaminophen in a day (4). The significance of the fact that an alcoholic can safely use 3000mg per day of acetaminophen is that seemingly this medication is safe even in those with unhealthy livers when taken at the recommended doses.
Does acetaminophen affect the mood? Some people may notice that acetaminophen affects their mood. And in fact some researchers have discovered that it does in fact seem to blunt emotional reactions to both positive and negative stimuli (5). This blunting effect on emotional reactions may or may not be noticeable, useful, or harmful. But the possibility of acetaminophen affecting the mood is there.
Acetaminophen will continue to be as common as color TVs, credit cards and seat belts. It has proved to be useful and safe; thus, acetaminophen is here to stay.
1.Toes MJ; Jones AL; Prescot L; Drug interactions with paracetamol; American Journal of Therapeutics; 2005 Jan-Feb;12(1):56-66;
_2._Krenzelok EP; Royal MA; Confusion acetaminophen dosing changes based no evidence in adults; Drugs in R&D; 2012 Jun 1;12(2):45-8
3.Ioannides SJ; Siebers R; Perrin K; et al; The effect of 1 g acetaminophen twice daily for 12 weeks on alanine transaminase levels-A randomized placebo-controlled trial; Clinical Biochemistry; 2015 Apr 18. pii: S0009-9120(15)00135-6
4.Bartels S; Sivilotti M; Crosby D; Richard J; Are recommended doses of acetaminophen hepatotoxic for recently abstinent alcoholics?; Clinical Toxicology (Philadelphia PA); 2008 Mar;46(3):243-9
5.Durso GR; Luttrell A; Way BM; Over-the-Counter Relief From Pains and Pleasures Alike; Acetaminophen Blunts Evaluation Sensitivity to Both Negative and Positive Stimuli; Psychological Science; 2015 Apr 10
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Christina Lasich, M.D., wrote about chronic pain and osteoarthritis for HealthCentral. She is physiatrist in Grass Valley, California. She specializes in pain management and spine rehabilitation.