Acetaminophen, brand name Tylenol, also known as paracetamol in Europe, is a fever reducer and analgesic medication that is sold over the counter or prescribed in combination with narcotic pain relievers. Like nonsteroidal anti-inflammatory drugs, acetaminophen inhibits prostaglandin synthesis, but does not reduce inflammation in most tissues and is not regarded as a blood-thinner. Tylenol is not linked to the development of Reyes syndrome, and, therefore, is approved for use in children. Acetaminophen is thought to be less likely to cause stomach upset and is generally considered safer during pregnancy than aspirin and ibuprofen.
Liver Damage
Acetaminophen overdose is associated with acute liver failure, and is a leading cause of liver transplant in the United States. The use of the maximum daily recommended dose of acetaminophen for as long as two weeks may trigger the release of liver enzymes in the blood, an indication of potential liver damage. Researchers at the University of North Carolina conducted a randomized, placebo-controlled study of 145 healthy adults who took four grams of acetaminophen daily, the equivalent of eight extra-strength Tylenol pills, for 14 days. Liver enzymes were found to reach three times the normal levels while taking acetaminophen, and remained elevated even after the medication was discontinued and was no longer detectable in the body. The findings were published in the July 2006 issue of "Journal of the American Medical Association." Drinking alcohol may increase the risk of acetaminophen-induced liver damage.
Asthma
As part of the International Study of Asthma and Allergies in Childhood, New Zealand researchers studied 205,487 kids in 31 countries and found that acetaminophen use for fever during the first year of life was associated with increased asthma symptoms by age six or seven. Additionally, the frequency of current acetaminophen use was correlated with more severe asthma, as well as runny nose, itchy eyes and eczema. The study was published in the September 2008 issue of "Lancet." In January of 2010, "Clinical and Experimental Allergy" published the conclusions of other New Zealand researchers who assert that a dose-dependent relationship exists between infants born to mothers who used acetaminophen while pregnant and asthma in infancy, later childhood and adulthood. The scientists believe acetaminophen use may alter immune response in all stages of life.
Gastrointestinal Complications
Researchers in Madrid, Spain followed 2,105 patients and 11,500 controls over five years to determine the risk of upper gastrointestinal complications such as bleeding and perforation in the stomach or duodenum that could be associated with analgesic medications. Daily use of more than two thousand milligrams of acetaminophen for 30 days was associated with a higher risk of gastric injury. The risk increased to eight times more than normal when acetaminophen was combined with nonsteroidal anti-inflammatory medications such as ibuprofen or naproxen. The findings were published in 2001 in "Arthritis Research."
References
- "JAMA"; Aminotransferase Elevations in Healthy Adults Receiving 4 Grams of Acetaminophen Daily: a Randomized Controlled Trial, Watkins PD, et. al., July 5, 2006, 296(1)
- "Lancet"; Association Between Paracetamol use in Infancy and Childhood, and Risk of Asthma, Rhinoconjunctivitis, and Eczema in Children, Beasley R, et. al., Sept 20, 2008, 372(9643)
- "Clinical and Experimental Allergy"; The Role of Paracetamol in the Pathogenesis of Asthma, Farquhar H., et. al., January 2010, 40(1)
- "Arthritis Research"; The Risk of Upper Gastrointestinal Complications Associated with Nonsteroidal Anti-Inflammatory Drugs, Glucocorticoids, Acetaminophen, and Combinations of These Agents, Garcia Rodrigues, LA, et. al., 2001, 3(2)
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