# Why and how to acetaminophen and ibuprofen damage the stomach/lungs? **URL:** \ **Category:** Factual Questions\ **Created:** [December 31, 2014, 2:15pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614 "2014-12-31T14:15:28Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Cardboard](https://avatars.discourse-cdn.com/v4/letter/c/49beb7/32.png) [@Cardboard](https://boards.straightdope.com/u/Cardboard)\ **Post date:** [December 31, 2014, 2:15pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/1 "2014-12-31T14:15:28Z")
We all know the warnings: Don’t take too much acetaminophen/ibuprofen or your stomach will bleed and your liver will rupture. Or something. Why and how do those drugs cause such damaging effects (if taken in large enough quantities)? ---
**Author:** ![boffking](https://avatars.discourse-cdn.com/v4/letter/b/858c86/32.png) [@boffking](https://boards.straightdope.com/u/boffking)\ **Post date:** [December 31, 2014, 2:18pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/2 "2014-12-31T14:18:24Z")
Do acetaminophen and ibuprofen damage the lungs? I have never heard of that happening. ---
**Author:** ![Cardboard](https://avatars.discourse-cdn.com/v4/letter/c/49beb7/32.png) [@Cardboard](https://boards.straightdope.com/u/Cardboard)\ **Post date:** [December 31, 2014, 2:24pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/3 "2014-12-31T14:24:38Z")
Nope…I meant to say liver, but for whatever reason I said lungs. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [December 31, 2014, 2:38pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/4 "2014-12-31T14:38:36Z")
I don’t know much about the mechanism, but I thought acetaminophen wasn’t as hard on the stomach as aspirin and ibuprofen. It might hit the liver worse, especially if you exceed the max daily dosage. ---
**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\ **Post date:** [December 31, 2014, 2:40pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/5 "2014-12-31T14:40:44Z")
You’re asking two different questions. NSAIDS (like ibuprofen) and Tylenol (acetaminophen) are in different drug classes. NSAIDs (like ibuprofen) are damaging to the stomach lining because of their mechanism of action blocking the COX-1 and COX-2 enzymes which prohibits the production of protective prostaglandins. Additionally, NSAIDs are directly irritating to the mucosal lining of the stomach and duodenum. Tylenol is toxic to the liver (doesn’t cause you’re liver to rupture though, never heard of that) because of the way the liver metabolizes acetaminophen. One of the metabolytes of Tylenol (NAPQI) is toxic to the liver. Under normal circumstances it is produced in small quantities but in some cases (such as Tylenol overdose or concomitant use of other substances like alcohol) NAPQI is produced in larger quantities and causes liver damage. ---
**Author:** ![Cardboard](https://avatars.discourse-cdn.com/v4/letter/c/49beb7/32.png) [@Cardboard](https://boards.straightdope.com/u/Cardboard)\ **Post date:** [December 31, 2014, 3:23pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/6 "2014-12-31T15:23:09Z")
> [@USCDiver](#): > > You’re asking two different questions. NSAIDS (like ibuprofen) and Tylenol (acetaminophen) are in different drug classes. > > NSAIDs (like ibuprofen) are damaging to the stomach lining because of their **mechanism of action blocking the COX-1 and COX-2 enzymes which prohibits the production of protective prostaglandins.** Additionally, NSAIDs are directly irritating to the mucosal lining of the stomach and duodenum. so…what does that mean ---
**Author:** ![Chief\_Pedant](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@Chief\_Pedant](https://boards.straightdope.com/u/Chief_Pedant)\ **Post date:** [December 31, 2014, 3:25pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/7 "2014-12-31T15:25:24Z")
In simple terms, acetaminophen is mostly metabolized (broken down) by the liver through a series of steps. One of the steps produces a toxic intermediary which is in turn processed and excreted. Too much acetaminophen overwhelms the liver’s ability to detoxify the intermediary, so damage results. Nice technical article [here.](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2836803/) [Here](http://www.hindawi.com/journals/mi/2013/258209/) is a summary for NSAIDS and stomach injury. Section 4 in the article talks about the mechanism. NSAIDS can inhibit the synthesis of enzymes which are necessary to help the stomach lining be protected from acid, and they also can directly damage stomach lining cells. They may also increase the formation of inflammatory mediators. ---
**Author:** ![Lasciel](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lasciel](https://boards.straightdope.com/u/Lasciel)\ **Post date:** [December 31, 2014, 4:09pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/8 "2014-12-31T16:09:59Z")
Non-techy version for stomach problems: Your stomach is full of really godawful acids, and normally the stomach is protected from that acid two ways: it’s lined with a lovely mucus-ey layer and there are some enzymes (basically chemicals that break stuff down) that specifically counteract the acid. NSAIDS do two things: they irritate that lovely mucus, and they also screw up the enzymes. Either of those isn’t too bad, but combined, they can cause real damage, especially if you’ve already got stomach troubles or you take too much and don’t give the stomach time to recover itself. ---
**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\ **Post date:** [December 31, 2014, 6:50pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/9 "2014-12-31T18:50:36Z")
Thank you all for providing both the scientific explanation and the layman’s versions. ---
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [December 31, 2014, 7:25pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/10 "2014-12-31T19:25:00Z")
> [@USCDiver](#): > > Under normal circumstances it is produced in small quantities but in some cases (such as Tylenol overdose or concomitant use of other substances like alcohol) NAPQI is produced in larger quantities and causes liver damage. Specifically, when you regularly drink a moderate to heavy amount of alcohol (2 - 4+ drinks), or at least for several consecutive days, your liver becomes more efficient at processing alcohol by producing more of the enzyme that breaks down alcohol (P-450 2E1). This is the same enzyme responsible for converting acetaminophen into NAPQI. If you have both alcohol and acetaminophen in your system at once, they are both competing for the same 2E1 enzyme, thus actually protecting your liver from damage. However, the danger is that if a heavy drinker suddenly stops drinking, like if they get the flu, and then takes the maximum daily dosage of acetaminophen (4 grams, I believe), all that extra 2E1 now has nothing to do but produce NAPQI, resulting in catastrophic liver failure. ---
**Author:** ![Cardboard](https://avatars.discourse-cdn.com/v4/letter/c/49beb7/32.png) [@Cardboard](https://boards.straightdope.com/u/Cardboard)\ **Post date:** [December 31, 2014, 7:37pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/11 "2014-12-31T19:37:29Z")
> [@purplehorseshoe](#): > > Thank you all for providing both the scientific explanation and the layman’s versions. I concur. Thanks all. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [December 31, 2014, 7:49pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/12 "2014-12-31T19:49:13Z")
Damn! You mean combining EtOH and a pain med is actually a GOOD idea? I can now check off one of those “Want to live long enough to see… 's”. Was I given inaccurate info, or was the therapeutic dosage for acetaminophen was 600-800 mg? ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [December 31, 2014, 7:55pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/13 "2014-12-31T19:55:40Z")
nm Found this Usual Adult Dose for Pain General Dosing Guidelines: 325 to 650 mg every 4 to 6 hours or 1000 mg every 6 to 8 hours From [Drugs.com](http://www.drugs.com/dosage/acetaminophen.html#Usual_Adult_Dose_for_Pain) But, since I was drinking like a fish at the time…Whoopee! a Freebie! (of course, my kidneys ae shot, but that is probably a 165/125 bp.) ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [December 31, 2014, 9:27pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/14 "2014-12-31T21:27:24Z")
Prostaglandins are a class of signaling molecules. They do a few different things. Those made by the enzyme COX2 (cyclooxygenase II) signal pain and cause inflammation. Those made by COX1, a closely related enzyme, are involved in maintaining the stomach lining, among other things. NSAIDs inhibit both COX1 and COX2. This is why molecules that selectively inhibit just COX2 (like Vioxx) were such a big exciting deal a few years ago. They held the promise of relieving pain without the bad side effects. Unfortunately, they turned out to have unexpected side effects and had to be withdrawn. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [December 31, 2014, 10:21pm UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/15 "2014-12-31T22:21:20Z")
> [@usedtobe](#): > > Damn! > > You mean combining EtOH and a pain med is actually a GOOD idea? No. Not at all. It’s just not as damaging as taking after stopping drinking altogether. Taking acetaminophen and alcohol at the same time is still a bad idea, as there’s no guarantee the processing has sped up enough to handle it. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [January 1, 2015, 3:29am UTC](https://boards.straightdope.com/t/why-and-how-to-acetaminophen-and-ibuprofen-damage-the-stomach-lungs/708614/16 "2015-01-01T03:29:08Z")
Hey - I was _very_ careful to always get a running start before dropping the NSAIDs!