Acetaminophen is a common over the counter pain medicine. Acetaminophen (in painkillers such as Tylenol) is present in hundreds of products and may sometimes be unsafe even when used at the maximum daily doses recommended on package labeling. Acetaminophen (APAP) is the most common drug overdose in pregnancy. Acetaminophen (Tylenol, others) isn't an NSAID, but it sometimes does reduce pain and fever. Unlike the NSAIDs, however, acetaminophen does not reduce inflammation.
   The words acetaminophen and paracetamol both come from the chemical names for the compound: N-acetyl-para-aminophenol and para-acetyl-amino-phenol. In some contexts, it is shortened to apap, for N-acetyl-para-amino-phenol.

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Acetaminophen safety - Acetaminophen side effects - Acetaminophen toxicity
Taken occasionally and in dosages less than 500 mg, acetaminophen has few side effects and is generally safe. However, if you frequently take more acetaminophen than is recommended side effects can occur. Taking a large dose of acetaminophen with alcohol increases the side effect risk and can lead to sudden and severe problems, such as liver failure. Acetaminophen is included in many different medications for pain, headaches, colds and sleep aids. Be sure to read the ingredients listed for all your medications to make sure you are not consuming more acetaminophen than you realize.
   Additional acetaminophen side effects include diarrhea; increased sweating; loss of appetite; nausea or vomiting ; stomach cramps or pain; swelling, pain, or tenderness in the upper abdomen or stomach area.

Acetaminophen and liver toxicity
More than a third of healthy adults starting acetaminophen / paracetamol at the maximum recommended daily dosage of 4 grams will exhibit ALT liver enzyme elevations. The lead researcher is Dr. Paul B. Watkins, from the University of North Carolina in Chapel Hill. Dr. Watkins's study involved 145 healthy adults who were randomized to receive acetaminophen alone, acetaminophen plus opioid in one of three combinations, or placebo for 14 days. In all of the acetaminophen groups, the acetaminophen dosage was 4 g/day. No ALT elevations greater than three times the upper limit of normal were seen in the placebo group. By contrast, the incidence of such elevations ranged from 31% to 44% in the four groups receiving acetaminophen. As noted, treatment with opioids did not further increase the ALT elevation seen with acetaminophen. Serum acetaminophen levels were usually not measurable at the time of the elevation. JAMA 2006;296:87-93.

Liver Failure Acetaminophen side effect
In patients with acute liver failure, a test can determine whether acetaminophen toxicity is involved. More than 56,000 emergency room visits and nearly 500 deaths in the US each year are attributed to acetaminophen toxicity, owing to either intentional or unintentional overdoses. Acetaminophen toxicity is currently the most common cause of acute liver failure in the US and Europe. Although intentional acetaminophen overdose is fairly easy to diagnose, in unintentional overdoses, the diagnosis can be elusive, leading to a delay in the administration of potentially life-saving treatment. In animal and human studies, "serum acetaminophen-protein adducts" or mutations, are specific biomarkers for drug-related toxicity. Gastroenterology March 2006.

Acetaminophen and Osteoarthritis
The evidence to date suggests that NSAIDs are superior to acetaminophen for improving knee and hip pain in people with osteoarthritis. In fact, it is possible that chronic use of acetaminophen could harm or cause damage to articular tissue, or, at the least, harm liver tissue. For osteoarthritis pain and joint health, glucosamine and chondroitin are preferred.

Acetaminophen and tooth extraction
Paracetamol (Panadol) , the pain killer known as acetaminophen in the U.S. and sold under the trade names Tylenol in the US and Panadol in the UK, is an effective treatment for the pain following wisdom tooth extraction.

Acetaminophen Drug Recall
November 2006 - Perrigo Co.. a major manufacturer of store-brand acetaminophen, recalled 11 million bottles of the pain-relieving acetaminphen pills after discovering some acetaminophen pill were contaminated with metal fragments. There were no immediate reports of injuries or illness. Perrigo Co. said it discovered the metal bits during quality-control checks. The drug company passed 70 million acetaminophen pills through a metal detector and discovered the metal in about 200 caplets. The fragments ranged in size from “microdots” to portions of wire one-third of an inch long. Perrigo company did not disclose the chains for which it manufactures the store-brand acetaminophen.

Acetaminophen questions
Q. I would like to use acetylcysteine to protect my liver from the amount of acetamenophin I am required to take on a daily basis due to my injuries. How much would I need to take of acetylcysteine?
   A. We have not seen any studies regarding the long term use of acetaminophen and acetylcysteine, however a dose of 100 mg a day would seem reasonable.

Q. People who are addicted to pain medications, such as hydrocodone, often take way too much APAP (acetaminophen) in the process. For over a year, I was one of them. I averaged over 30 10/325 tablets a day, often taking much more (several times 80 or more). Knowing what I was doing to my liver, I researched the procedure used in the ER for acetaminophen overdose and proceeded to treat myself accordingly, using OTC NAC (n-acetylcysteine). I am thankfully free of this addiction now (over 9 months), but still communicate with others in the throws of it. I have suggested to them that they should stock up on N-acetyl Cysteine and use it if necessary (obviously the right solution is to go straight to the ER if you've taken over 10g of acetaminophen, but we both know that may not happen with these folks). When I pointed this out, I was overwhelmingly ridiculed and dismissed by those who said the NAC available over the counter is nothing like that used in the ER. I know there is probably a difference, but given that one is not going to seek proper medical treatment, isn't the NAC we have access to a great alternative? What exactly is the difference between the two formulations?
   A. Based on my limited knowledge, since I have not seen head to head research comparisons, I tend to think that the benefits of oral and intravenous NAC would not be too different, but I have no proof of this.

Q. I recently read that taking echinacea with acetaminophen" can severely damage your liver" and that taking kava kava or echinacea while on a statin med for cholesterol "can trigger potentially fatal liver damage". (These statements were attributed to a book by George Grossberg, M.D.) Are these statements supported by the available evidence? I am on a statin and sometimes take acetaminophen for arthritis pain.
   A. We have not heard of echinacea causing serious liver harm, perhaps in rare cases. Acetaminophen can certainly harm the liver, statins could, and kava may in rare cases. The combinations would not be a good idea.

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