The People's Perspective on Medicine

Is Acetaminophen (Tylenol) and Warfarin A Scary Combination?

Acetaminophen is perceived as super safe. But when you combine acetaminophen (Tylenol) and warfarin it is possible you could develop a dangerous bleeding problem.

People who have to take a blood thinner like warfarin (Coumadin) are caught in a terrible double bind. If they have pain, they have surprisingly few options. That’s because NSAIDs like ibuprofen (Advil, Motrin IB, etc) or naproxen (Aleve) can cause irritation and lesions within the GI tract. An anticoagulant like warfarin can lead to a bleeding ulcer. What about Acetaminophen (Tylenol) and warfarin? For far too long health professionals assumed this combination was safe. This reader has concerns about drug interactions:

How Safe is “Low-Dose” Acetaminophen with Warfarin?

Q. I am on warfarin and suffer from arthritis pain daily. My doctor said I could safely take Tylenol in small amounts.

But I read in your column that taking Tylenol with warfarin is dangerous. I feel like dropping the warfarin so I could treat my pain, but that isn’t an option. So I’m stuck between a rock and a hard place. What can I take for pain relief?

How Dangerous is Acetaminophen (Tylenol) and Warfarin?

A. You have identified a serious problem for people on the anticoagulant warfarin (Coumadin, Jantoven). More than two grams of acetaminophen (Tylenol) per week could increase the possibility of a dangerously high INR lab reading (Journal of Pharmacy Practice, Oct. 2013).  The INR, or International Normalized Ratio, is a measure of anticoagulant activity. One day’s worth of acetaminophen for arthritis would exceed the recommended two-gram limit.

How much is two grams of acetaminophen? If you look on the label of Extra Strength Tylenol containing 500 mg of acetaminophen per pill, you will see that the makers state that adults can take no more than 6 pills per day (3,000 mg). That is a change from the old 8 pills per day (4,000 mg). The company also notes that:

“The dosing interval has also changed from 2 pills every 4 – 6 hours to 2 pills every 6 hours.”

So, in one day it is possible to exceed the two grams (2,000 mg) dose that was noted to cause problems in the Journal of Pharmacy Practice article above.

People’s Pharmacy Perspective:

Although combining acetaminophen (Tylenol) and warfarin has long been thought to be safe, we now think differently. An article in Pharmacy Times (February 27, 2017) was titled:

Acetaminophen and Warfarin: The Forgotten Interaction

The authors note:

“Numerous case reports have been published that describe patients taking warfarin who experienced supratherapeutic INRs and bleeding events after taking moderate-to-high doses of acetaminophen for multiple days.  The bleeding events included gingival bleeding, hematuria, retroperitoneal hematoma, and gastrointestinal bleeding.  International normalized ratios (INRs) ranged from 4.0 to 16.39 in the studies, with one study reporting a patient who had a prothrombin time (PT) of 96 seconds.”

In English that means that this drug combination has led to bleeding gums, blood in the urine and abdominal bleeding, These are not good outcomes.

What Can People in Pain Do?

Your doctor might be able to prescribe a different anticoagulant. Some of the newer (and pricier) ones do not appear to interact with acetaminophen. This is a conversation that requires homework. We understand how cautious you must be at monitoring your INR values to prevent hemorrhage on the one hand or a blood clot on the other.

Stories from Readers:

Other visitors to The People’s Pharmacy website have shared their frustration about acetaminophen (Tylenol) and warfarin.

Zipora in Boston, MA had a close call:

“I have been on Coumadin for the last few months for an Afib condition. I fell and fractured my sternum. I took Tylenol for the pain not knowing the interaction.

“I was of town and had to go the ER because the pain did not subside, and I had black and blue marks on my body. My INR was 5. They stopped the Coumadin for two days and gave me another pain med, Norco [an opioid].

“Well, my INR returned to a normal value of 2.4, and I am recovering from the fractured bone. No one ever warn me not to take Tylenol with Coumadin. It shows that physicians don’t know all the effects of drugs. I figured out the drug interaction on my own but the People’s Pharmacy confirmed it .”

Brigitte in British Columbia has to be vigilant:

“I agree the Tylenol is definitely not compatible with warfarin. This is the 2nd time my mom has taken Tylenol arthritis every day for pain on her doctor’s recommendation, and both times, her INR went up from normal range 2.4 to out of range 3.4. Last time, it went to 3.7. I am going to try to educate her doctor at the next appointment. I hope he listens this time.”

Gloria also had a close call because of cold medicine:

“This is happening to me. I take Coumadin for a heart valve. I have had a cold this week with headache and bodyaches. I have been taking Tylenol – maybe two or three 500 mg capsules per day. My INR is normally around 2.5. It was 3.7!

“I have also been taking some cough meds. So not sure if Tylenol alone or the combination is the problem. My INR is very high.

“My doctors have also told me it’s ok to take Tylenol. I need to rethink that! Maybe one now and then only.”

You can read more about this interaction at this link.

Share your own acetaminophen (Tylenol) and warfarin story below in the comment section.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” .
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Have been on warfarin for twenty years; have been using acetaminophen to combat pain (arthritis) after some surgeries. In fact I take 2 650 mg extend-release tablets each and every night to sleep. I have no problems with liver or kidney functions and just received a clean bill of health from my Doctor.

My husband had been on Warfrin quite a while after ablation, open heart surgery, two valves replaced, on 3rd pace maker. He fell down yesterday and hit his head and landed on his right hip, which instantly turned into a football-sized hematoma. I gave him 1. 500 mg Tylenol twice during the day. Today we ended up at the hospital with his IR at 4.9. He has been sick since Christmas with a bad cold, so I am unsure what caused the high reading. Could it be all
the cough medicine or the Tylenol that created the problem? Tomorrow we will have more tests done.

YES… One of the 1st things Afib patients are told (over and over!) is that NSAIDS are verboten as they can cause not only GI problems but also heart problems and increased stroke risk. In fact, I’ve even heard that NSAID use can trigger the onset of Afib in some people. So, what’s a person to do if they also cannot take acetominaphen (Tylenol)?

I did have Afib some years back. But not anymore, because I got an ablation! But when I was taking Warfarin (also a beta blocker called Sotolol), I did use Tylenol for skiing or backpacking aches and never noticed any ill effects. I DID notice, however, that I had MUCH less strength and stamina on those terrible meds. As soon as I stopped them, the stamina came springing right back. People, if you have any chance to get a cardiac ablation for your Afib, do it! You’ll be glad you did.

I have not noticed any of the noted side effects and my INR readings are usually within my goal range (2.0 – 3.0). I take Warfarin daily and Acetaminophen whenever I have minor pains. Usually one 500 mg tablet twice a day is enough to relieve the pain. I always research medications before I take them because doctors are not always up to date on the latest drug / drug interactions recommendations.

I too am on Warfarin and have arthritis and and take acetaminophin 500 mg only occasionally but have found that roll on Salonpas with Lidocaine has relieved the pain.
What about the Hemp rub ?

Just a thought in passing. My dad passed away at the age of 75 years. He was notorious for taking a small amount of baking soda, used in cooking, to eliminate stomach acid or “heartburn”. He would let out a loud burp and bingo, it was over. I know how violent the reaction is between baking soda and battery acid (sulfuric acid), so is that violent reaction the same in the stomach when baking soda is taken. Just curious.

Your writer from Boston with the fracture should note that Norco is a combination of an opioid and acetaminophen.

Monitor your inr weekly at home. I have used Alere home monitoring for over a decade. They supply the same test meter the clinic uses. Medicare pays most of cost and the cost is much less than the clinic. No waiting in doctors’ offices with sick patients. You can do it yourself. Weekly monitoring will help you keep your inr within range. Use as many of the warfarin dosage pills (2mg,3mg,4mg,5mg) to make as small as possible daily dosage adjustments. I make my daily adjustments in .50mg adjustments. The first clinic wanted to use one 5mg pill and adjust 2.5mg and every six weeks too. Alere will help with the paperwork. I had to walk the paperwork to two doctors for their signature. It was clear that the two clinics and doctors’ personnel did not want this to be easy for me.

I have been taking Warfarin for 20 years for DVT problems, now suffering from Arthritis in most bones (old age). I need some form of analgesic for pain relief on a regular basis. Apart from useless paracetamol what is open to me? Am now knocking on the gates of 80 years. There have to be some comparable pills!

Back in the 1940’s, a Dr. William Kauffman (Ph.D. and M.D.) researched the effects of large doses of Niacinamide on osteoarthritis and found it to be highly effective in relieving the pain. I’ve been trying this out over the past two weeks and my arthritis pain is almost gone. I’m taking 2500 mg. a day (well above the Daily Value) with no apparent side effects and the pain in my hands and joints is all but gone. There are numerous references to Dr. Kauffman’s work on the Web, and he’s written several books about his research.

I’m 72, and for the last seven years or so I’ve made it a practice to always look up a prescribed drug before taking it, whether in the PDR (Physician’s Desk Reference) or on the Internet. It’s remarkable how little doctors actually know about the drugs they prescribe or about the nutritional basis of so many human ailments. I once suffered through a mysterious lung infection that was caused by taking aspirin with an antidepressant called Pristiq. After many doctor visits, antibiotics, and tests, I found my true diagnosis in a drug company TV ad that warned against combining the two due to possible excessive bleeding. Today, I’m handicapped by severe shoulder damage from taking a statin drug, unnecessarily I believe, for borderline “high” cholesterol, a number decreed by the very company that makes Lipitor. I can’t stress enough how important it is to look out for yourself rather than trustingly take whatever drug or “procedure” is prescribed.

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