Acetaminophen and Warfarin

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Seeker

Seeker

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Jan 16, 2016
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After my St. Jude mechanical valve placement my doctors advised me I can no longer take any NSAIDs like ibuprofen (Advil, Motrin, etc) or naproxen (Aleve) as they are antagonistic with Warfarin. I've been taking Acetaminophen (Tylenol) as needed for many years since my mechanical valve placement and never thought much about an interaction thinking it was "safe" to take alongside with Warfarin. Last night and the night before I took 1000mg of Tylenol before bed to counter some pain I was having. I self tested at home today (for my monthly INR clinic call in) and it was at 4.0. My target INR range is between 2.0 and 3.0. Has anyone here had any INR issues with Acetaminophen?
 
Hi

firstly, I recommend you read this thread

https://www.valvereplacement.org/threads/ibuprofen.887853/#post-902218

So basically "not so much" ... but do as I did and self test to check how *you* react
secondly we know that as Paracetamol

https://en.wikipedia.org/wiki/Paracetamol

This is widely documented as raising INR with larger doses and also when taken for multiple days.

Paracetamol: a haemorrhagic risk factor in patients on warfarin​

Results​

In patients on paracetamol, the mean maximum increase in the International Normalized Ratio (INR) observed was 1.04 ± 0.55 vs. 0.20 ± 0.32 in those on placebo (P = 0.003). The mean maximum INR observed was significantly higher with paracetamol than with placebo (3.47 vs. 2.61, P = 0.01). In patients receiving paracetamol, the mean observed INR was significantly increased after 4 days (+ 0.6 ± 0.6, P < 0.001).​

Conclusion​

Paracetamol at 4 g day−1 induces a significant increase in INR in patients receiving a stable regimen of warfarin,​

however
Seeker said:
Last night and the night before I took 1000mg of Tylenol before bed to counter some pain I was having
Click to expand...

this isn't much (I usually have 500mg and perhaps 1000) followed by 500mg 4 or so hours later if something is uncomfortable. So I would ask:
  1. what is your frequency of testing (this could be a coincidence)
  2. have you had anything else (like grapefruit juice).

Best Wishes
 
Last edited:
  1. what is your frequency of testing (this could be a coincidence)
I test about once month when my INR is stable. In this instance I'll get tested again in 2 weeks.
  1. have you had anything else (like grapefruit juice).
No juice.

I've also started taking 81mg of aspirin daily. I've read that aspirin has no effect on the INR however, I read the link you attached which references "aspirin/paracetamol/caffeine." I do consume a lot of coffee. Nearly a pot a day. I'm not sure if that combination would raise my INR.
 
Seeker said:
I test about once month when my INR is stable. In this instance I'll get tested again in 2 weeks.
Click to expand...
personally I can't agree that in this instance 2 weeks is sufficient ... however if you're not self testing then you're driving without looking in the rear vision mirror when you change lanes or looking before crossing the road. Works well sometimes. I ride with a helmet and wear a seatbelt, every time.

Glad to hear there was no grapefruit

I've also started taking 81mg of aspirin daily. I've read that aspirin has no effect on the INR however,
Click to expand...
correct ... it does not effect INR at all as it effect platelets not thrombin.

I read the link you attached which references "aspirin/paracetamol/caffeine." I do consume a lot of coffee. Nearly a pot a day. I'm not sure if that combination would raise my INR.
Click to expand...
not sure I remember that link, but "nearly a pot" has no meaning without at lest "how much coffee grounds is in there"; however I've never read of or seen an interaction mentioned about coffee (or tea).

Something else is at work here and I anticipate that it was perhaps high for some time and you just didn't know it.

Self testing gives you a test for about $6, so its pretty hard to say that's too much per week.

I hope that helps
 
pellicle said:
personally I can't agree that in this instance 2 weeks is sufficient ... however if you're not self testing then you're driving without looking in the rear vision mirror when you change lanes or looking before crossing the road. Works well sometimes. I ride with a helmet and wear a seatbelt, every time.

Glad to hear there was no grapefruit


correct ... it does not effect INR at all as it effect platelets not thrombin.


not sure I remember that link, but "nearly a pot" has no meaning without at lest "how much coffee grounds is in there"; however I've never read of or seen an interaction mentioned about coffee (or tea).

Something else is at work here and I anticipate that it was perhaps high for some time and you just didn't know it.

Self testing gives you a test for about $6, so its pretty hard to say that's too much per week.

I hope that helps
Click to expand...
Thanks pellicle. Your input on these matters is always appreciated. God bless.
 
Seeker said:
Thanks
Click to expand...
welcome

I (as it happens) just came back to post this:
1726035573282.png


you can see that my dose was really nicely in range for weeks (like from week15); yet around week 39 I had to adjust my dose down gradually to 5.5mg daily. If I'd been testing monthly my INR would probably have been over 5 for how ever long it was between tests.

Its stuff like this which is the reason why the stats on bleeds are as they are.

Now, granted its usually the case that as we age we have:
  • a lower dose requirement due to reduction in metabolic activity
  • a more stable metabolism
So its tempting ... but also as we age our vascular system becomes less "elastic" (like the rest of our skin) and we get strange and unexpected issues bring us to harm. For instance about a year back I had this

1726036079540.png


as it happened my INR was 2.4 (two days prior) so it wasn't caused by INR (actually they almost never are) but if my INR had been 4 I'm sure it wouldn't have ceased as fast. Three days later it was dispersing

1726036348649.png


I also went to the clinic in town and they said "that happens" ...

¯\_(ツ)_/¯

Best Wishes
 
Your post made me look this up since I take Tylenol every now and then, but never took more than 1000 mg a day. And so far, no effect on my INR.

HERES WHAT I FOUND IN BRIEF:

Taking 1000 mg of Tylenol (acetaminophen) while on warfarin is generally considered safe, BUT it’s not safe to take higher doses several times a day for several days in a row without doctor’s consultation/supervision.
 
Your doctor was wrong when he told you that NSAIDS are antagonistic to warfarin. What the NSAIDs do is make your platelets 'less sticky', which makes clotting take longer than if you haven't taken an NSAID.

I took a fair amount of tylenol last year when I had some broken ribs -- the tylenol/acetaminophen/paracetamol caused my INR to increase. The increase wasn't into a level that caused much concern, but I noticed the change. At least with this medication, you can see changes that may effect clotting - not like the effects of NSAIDs, which your meter won't see.
 
It’s interesting, since being put on Eliquis due to afib (vs the 325 mg aspirin I was on before) I actually have fewer problems with bruising. Will be on warfarin soon post valve replacement so will see how that goes.
 
My cardio and the hospital pharmacist said the problem with NSAIDs is they cause stomach bleeding in a significant number of people. This is very hard to control if you have an elevated INR thus all of them are contraindicated. I am allowed to take ibuprofen, but only at the lowest therapeutic dose, no higher than the maximum daily dose and no longer than 1-2 months.

I can take acetaminophen as long as I stay within the recommended dose. I believe it can cause liver or kidney problems if you take too much, but I haven't investigated it.
 
True, they can cause stomach bleeding. But there are enteric coated aspirin that are designed to NOT dissolve in the stomach - instead, these dissolve in the intestines -- thus, no stomach issues. I take 81 mg enteric coated aspirin - low dose - but haven't had problems with them.

I don't think 'stomach bleeds' are the biggest problem that NSAIDs cause -- NSAIDS affect the 'stickiness' of platelets, making it take longer to form clots. An E.R. doc, years ago, told me that the platelet thing was an issue with NSAIDs. Doctors since then have also echoed the same thing.

Although NSAIDS certainly CAN cause stomach bleeds if too much is taken, or if a person is particularly sensitive to them, I don't think that this is the main reason to avoid them.
 
I thought aspirin had an impact on platelets ability to clot due to reduced prostaglandins but NSAIDS not as much. However, long term use of NSAIDS have an unfortunate side effect of stomach issues including bleeding . I’m not as familiar with the interaction of NSAIDS with Coumadin but one of the reasons I went with bio valve was because I due require anti inflammatory meds for other muscle skeletal issues. My view into the future was a risk of internal bleeding while on Coumadin. Flip the coin, uncontrollable pain or possibly (probably) requiring another valve in the future. It was a difficult decision.
 
Hi

Survived03 said:
I thought aspirin had an impact on platelets ability to clot
Click to expand...
correct

https://www.healthline.com/health/thrombocytopenia-and-aspirin

Aspirin reduces the ability of your platelets to stick together to form a clot by blocking the activity of an enzyme called cyclooxygenase-1 and reducing the synthesis of a molecule called thromboxane A2. Blocking the formation of thromboxane A2 prevents exposed platelets from becoming activated over their lifetime​

so as I understand it the exposure to the aspirin damages the platelets present for their life (about 10 days); but as this is a cyclical thing (always some being produced rather than a brief pulse of them all being replaced like a changing of the guard) you'll have some in there that are OK soon after the aspirin is gone (about two hours).

This is my personal rationale for taking aspirin ever second day.

Survived03 said:
I’m not as familiar with the interaction of NSAIDS with Coumadi
Click to expand...

Nothing direct that I'm aware of ... however

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8002800/

NSAIDs are second to Helicobacter pylori infection in causing peptic ulceration in the upper GI tract. They cause mucosal injury due to cyclo-oxygenase (COX)-1 inhibition by reduction of cytoprotective mucosal prostaglandins and reduction of the secretion of a protective bicarbonate mucus barrier in the stomach and small bowel.​
​
A third of patients consuming NSAIDs develop foregut symptoms of dyspepsia (epigastric discomfort, bloating, post-prandial nausea, early satiety and belching) and gastroesophageal reflux (heartburn and regurgitation). Such symptoms are not predictive of mucosal injury with 20% of symptomatic patients having a normal oesophagogastroduodenoscopy (OGD).​

so yes, being on NSAIDs isn't a good thing long term

So its not really an "interaction" so much as "combination of one thing causing damage (the NSAID) and the other thing exacerbating that" (the anticoagulant).

Seems to be splitting hairs but to me an interaction is different (maybe I'm wrong).

Survived03 said:
My view into the future was a risk of internal bleeding while on Coumadin.
Click to expand...
again, not meaning to be splitting hairs, a GI bleed isn't actually an internal bleed; because what goes into your mouth (and comes out your anus) isn't going into your body. Swallow a marble and it comes out. Neither food nor faeces is in your body.

This does not mean that I think a GI bleed is not threatening ... they can be very hard to treat and people I know have nearly died from them.

Best Wishes
 
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Survived03 said:
I thought aspirin had an impact on platelets ability to clot due to reduced prostaglandins but NSAIDS not as much. However, long term use of NSAIDS have an unfortunate side effect of stomach issues including bleeding . I’m not as familiar with the interaction of NSAIDS with Coumadin but one of the reasons I went with bio valve was because I due require anti inflammatory meds for other muscle skeletal issues. My view into the future was a risk of internal bleeding while on Coumadin. Flip the coin, uncontrollable pain or possibly (probably) requiring another valve in the future. It was a difficult decision.
Click to expand...
NSAIDS taken sporadically, are quite safe to use, not so much on a daily use. I rarely Tylenol. And only take 81 mg of aspirin due to eye stroke in 2016.
 
Not all NSAIDS have the same effect on platelets. According to a rheumatologist that I saw YEARS ago, Ketoprofen has the least effect on platelets.

Unfortunately, it's quite expensive - particularly when compared t the other NSAIDs, It's only available by prescription.

Because most drug plans see OTC NSAIDs as suitable alternatives. I don't think if ANY plans will pay much co-pay for it.
 
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