IV Tylenol Flops in Yet Another Pain Trial ... To No One's Surprise

By Josh Bloom — May 20, 2022
For reasons I cannot fathom, we are treated to yet another clinical trial about IV Tylenol and whether it can decrease the amount of morphine needed by pain patients in the ER. Here's your hint: No.
Image: Wikimedia Commons

Since I am nothing if not subtle, I was perfectly comfortable writing IV Tylenol As Good As Moose Urine For Post-Op Pain Control back in 2019, when I dissected a study that clearly showed that IV acetaminophen was thoroughly worthless in controlling post-operative pain following spinal surgery.

I fear that I will run out of ruminants long before IV Tylenol pushers run out of different body parts to study, hence the vegan-friendly title on this one.

So, what's today's Tylenol flop du jour? It's a study (1) in the journal Academic Emergency Medicine that makes short order of the question: "Can IV Tylenol reduce the amount of morphine needed by patients who visit emergency departments for pain relief?" (2)

You already know where this is going so I'll keep it short. 

The Study

  • 220 patients who visited the emergency department at Cantonal Hospital of St. Gallen in Switzerland were randomized into two equal groups, placebo and intervention (treated with Tylenol).
  • Both groups were blinded.
  • All had a Numerical Rating Pain Scale score of 4 or higher.
  • Patients in the morphine-only group received 0.1 mg of morphine per kilo of body weight) plus placebo (IV).
  • Patients in the treatment group received 0.1 mg of morphine per kilo of body weight plus 1.0 grams of Tylenol (both IV).
  • All the patients were dosed every 15 minutes until their pain scores were reduced to less than 4.

The Results (such as they are)

  • The Tylenol-plus-morphine group required a mean morphine dose of 0.15 mg ± 0.07 mg/kg and a total dose of 13.1 mg.
  • The morphine-only group required a mean morphine dose of 0.16 mg ± 0.07 mg/kg and a total dose of 11.7 mg.
  • These numbers are the same.

Other measured outcomes included the time required to control pain, the time for it to reoccur, and the frequency of side effects. Same. Same. Same.

The group also broke down the pain into different categories. Likewise, within these subgroups, there was (big surprise) no difference between the morphine and morphine + Tylenol groups:

Analysis Same. Same. Same. Same. Same. Same. Same.

  • No one got addicted (2).


Let's have the authors speak for themselves:

 In ED patients, acetaminophen had no additional effect on pain control or morphine sparing effect at the time of first morphine administration. Titrated morphine with the algorithm used was highly effective, with 80% of all patients reporting pain relief within 60 minutes of starting therapy.

Minotti, et. al.,  Acad Emerg Med (2022 May 2), doi: 10.1111/acem.14517. Online ahead of print.

Seriously, Folks

Don't you think that it's about time to knock this off? Do we really need to conduct more studies in the desperate attempt to find some use for Tylenol, especially if it can result in a reduction of one-bazillionth of a milligram of morphine? Knock it off. Please. I'm begging you.


(1) It's probably no accident that this trial took place in Switzerland. I can almost hear the screaming voices of the hoards of people who went to EDs with legitimate pain from legitimate medical issues only to be sent away with a healing crystal and pack of Tylenol (they work equally well). 

(2) Although I just made this up, I'm pretty sure no one got addicted from a lousy 17 mg of morphine. In fact, I'm so sure that I'm willing to bet my IRA against that of Dr. Andrew "Big Bling" Kolodny, who probably believes otherwise.

Josh Bloom

Director of Chemical and Pharmaceutical Science

Dr. Josh Bloom, the Director of Chemical and Pharmaceutical Science, comes from the world of drug discovery, where he did research for more than 20 years. He holds a Ph.D. in chemistry.

Recent articles by this author:
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