Is Tylenol (Acetaminophen) Bad for Your Liver or Kidneys?

Dr. Sharon Orrange
Dr. Orrange is an Associate Professor of Clinical Medicine in the Division of Geriatric, Hospitalist and General Internal Medicine at the Keck School of Medicine of USC.
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Acetaminophen (Tylenol) is one of the most commonly used medications so you should know if it hurts your liver or kidneys. The short answer: acetaminophen is safe on the kidneys and may damage your liver, but only at high doses. Here is what you need to know.

How much Tylenol can I take?

Acetaminophen is the generic name for Tylenol so they are the same thing. The recommended daily maximum is 4 grams per day, which would be 8 extra strength Tylenol (500 mg) or 12 regular (325 mg) Tylenol tablets. That’s the max. The regular dosing schedule is 325 mg – 650 mg every 6 hours or 1000 mg (two extra strength tablets) every 8 hours or twice a day.

Acetaminophen and the liver:

Acetaminophen is the leading cause of acute liver failure in the United States. What is important to know, however, is that liver failure almost always occurs at doses over 7.5 grams per day, which would be 15 extra strength (500 mg) Tylenol in a day. That’s a lot.

Is it bad for my kidneys?

No. Tylenol is broken down/metabolized almost completely by the liver, so the kidneys hardly do any of the work and are not affected by it. Acetaminophen is safe on the kidneys.

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The combo is the problem:

People get into trouble by not realizing that many over the counter and prescription meds have acetaminophen IN them. Acetaminophen works well for cold and flu symptoms, especially throat pain.

Seven out of ten Americans use over the counter (OTC) meds to treat cold and flu symptoms and many of these have acetaminophen in them. Be careful here and read the “Drug Facts” labels. Examples of OTC meds with acetaminophen: Theraflu, Excedrin Migraine, and Triaminic just to name a few. Read the label.

Prescription meds that contain acetaminophen are Ultracet, Vicodin, Fioricet, Percocet (the “cet” is the clue it has acetaminophen). There are new restrictions that limit the amount of acetaminophen to 325 mg in each tablet but realize when you are taking Vicodin or Norco you are also taking Tylenol.

What about alcohol?

Alcohol enhances the liver toxicity of acetaminophen. Consuming more than three alcoholic drinks a day may increase your risk of liver damage from tylenol.

And what about the liver again?

The work of breaking down acetaminophen is done by the liver so yes, at high doses, the liver can be affected. At regular doses, about 90% of acetaminophen is conjugated to form nontoxic metabolites. Another 5% is metabolized by the liver’s p450 enzyme to a toxic metabolite (NAPQI) which is then rapidly detoxified. The kidney does almost no work and just excretes the metabolites in the urine.

Dr O.

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