It’s getting confusing to take Tylenol. Tylenol (or acetaminophen) is a widely used analgesic both in Canada and the US. It has anti-pyretic properties and as such, it is very commonly prescribed for fever as well. It is also found in many combination medications:

  • Tylenol#3 contains acetaminophen and codeine (analgesic).
  • Tylenol Cold Day Time contains acetaminophen, dextromethorphan (cough suppressant), phenylephrine (decongestant).
  • Tylenol Cold Night Time contains acetaminophen, dextromethorphan (cough suppressant), phenylephrine (decongestant), chlorpheneramine (antihistamine).
  • Nyguil contains acetaminophen, dextromethorphan (cough suppressant), doxylamine (antihistamine).

So the market for Tylenol is HUGE and when we want to update its prescribing information, it gets complicated with too many stakeholders wanting to influence the decision.

In 2011, FDA made a recommendation to change the acetaminophen’s maximum daily dose limit from 4000mg per day to 3000mg per day. This was based on their own review of overdoses and liver toxicities related to acetaminophen and they thought lowering the maximum daily dose was wise. I assumed, at the time, Canada would follow the same decision as well. But it has taken Health Canada a lengthy process to consult relevant stakeholders, carry out meaningful discussions and finally coming out with a recommendation..hopefully soon.

It might have something to do with the criticism related to FDA’s decision to lower the maximum daily dose limit of acetaminophen – that it was not evidence based.  However, I suspect the greater influence was from the drug companies and manufacturers who must have been pressuring FDA to revisit the decision. After all, it would be an expensive decision to implement because it would cost drug companies lots of money to revise the product monographs, to review all packet inserts and to change the labeling on thousands of products that contain acetaminophen.

Recently, the FDA has taken a step back to acknowledge it may be safe to take acetaminophen as high as 4000mg/day.  Great. I look like an idiot now because I have been telling my physicians to reduce the daily dose limit of acetaminophen to 3000mg/day for the last few years.

Even if there is no concrete evidence taking acetaminophen up to 4000mg/day is unsafe, the important question is whether there is any incremental difference in pain control when the dose is increased from 3000mg/day to 4000mg/day.  If there is none, why take more?  I doubt if anyone will design a clinical trial to test out this question – definitely not in the best interest of the drug companies who make Tylenol or Tylenol containing products.  It also needs a very large sample size to detect this incremental difference. Why would anyone want to invest in such a study?

While in Canada, we still haven’t made up our mind. I am not surprised. We are a bit of a slow poke when it comes to these decisions. We like to look at our neighbours to see how they tackle the problems before we decide for ourselves.  Similar to the US, we may be looking at eliminating the extra strength (500mg) tablet to minimize the risk of overdose.  There is speculation that the maximum recommended daily dose limit may be as low as  2600mg/day (or 8 tablets of regular strength tablet of acetaminophen).  If the US intends to revert its decision on maximum daily dose limit back to 4000mg/day and Canada decides to set its limit to 2600mg/day, it is going to create a lot of confusion for the public. I can’t imagine how I can start explaining the difference.

Just thinking about all the conflicting information about Tylenol is making my head pounds. Maybe I need to take a Tylenol?  Oh wait, I can’t even keep straight how much Tylenol I can take anymore.

On second thought, I will take some Smarties instead.

 

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