Acetaminophen is commonly used as an antipyretic and pain reliever in young children and overall is quite safe considering the amount used by families for their children every day. Unfortunately, on occasion a therapeutic misadventure occurs and a young child develops severe acetaminophen induced liver injury. Compared to the incidence in adolescents and adults, healthy children less than 6 years of age rarely develop clinically significant liver injury from a one time, single, large, unintentional ingestion of acetaminophen. The high risk exposure is the infant/toddler who is receiving more than one supratherapeutic dosing of acetaminophen based products, usually for an acute febrile illness.
Two concentrations of over the counter pediatric liquid acetaminophen exist and families many times don’t realize that these pediatric dosages are not interchangeable. “Infant drops” are 100 mg acetaminophen per 1 mL (160 mg per 1.6 mL). The elixir formulations are 160 mg per 5 mL. As an example, if a parent gives a teaspoon (5 mL) of the infant formulation instead of the elixir, then the child receives a 500 mg dose of acetaminophen instead of 100 mg. If a supratherapeutic dosing pattern is continued every 4-6 hours over the course of a febrile ilness, then the child receives multiple administrations of high dose acetaminophen. This is the type of scenario that results in significant hepatic toxicity and may result in hepatic failure. In the absence of taking a specific history of the dosing regimen AND the concentration of the acetaminophen based product, the diagnosis may not be apparent, thus delaying the initiation of N-acetylcysteine therapy.
Numeracy and literacy skills may not prevent these unintentional exposures since most labels for pediatric acetaminophen products state to consult a doctor for dosing children less than 2 years of age. Families may choose to use the infant drops for their smaller children due to the perception that it is “safer” since it is labeled for infants, not recognizing that the primary difference is the concentration of the acetaminophen. Without specific direction from the healthcare community, families may assume that either formulation may be used for a dosing regimen calculated for the elixir (160 mg/5mL) product.
Question prepared by: Saralyn R. Williams, MD Medical Toxicologist
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Donna Seger, MD
Medical Director
Tennessee Poison Center
Website: www.tnpoisoncenter.org
Poison Help Hotline: 1-800-222-1222