Risk of unintentional overdose with non-prescription acetaminophen products.
BACKGROUND
There is increasing concern over the risk of consumer unintentional misuse of non-prescription (a.k.a. 'over-the-counter') medications containing acetaminophen, which could lead to acute liver failure.


OBJECTIVE
To determine the prevalence of potential misuse and overdose of over-the-counter medications containing acetaminophen, either alone or in combination.


METHODS
Cross-sectional, structured interviews with literacy assessment.


METHODS
One academic and one community-based general internal medicine practice in Chicago, IL, and one academic general internal medicine practice and a public hospital clinic in Atlanta, GA.


METHODS
Five hundred adults seeking primary care, ages 18-80.


METHODS
Demonstration of how and when patients would take over-the-counter medications containing acetaminophen, alone or in combination with one another, over a 24-hour period.


RESULTS
Overall, 23.8 % of participants demonstrated they would overdose on a single over-the-counter acetaminophen product by exceeding a dose of four grams in a 24-hour period; 5.2 % made serious errors by dosing out more than six grams. In addition, 45.6 % of adults demonstrated they would overdose by 'double-dipping' with two acetaminophen-containing products. In multivariable analyses, limited literacy (Relative Risk Ratio (RR) 1.65, 95 % Confidence Interval (CI) 1.03-2.66) and heavy acetaminophen use in the past six months (RR 1.70, 95 % CI 1.10-2.64) were independently associated with overdosing over-the-counter products.


CONCLUSIONS
Misunderstanding of the active ingredient and proper instructions for over-the-counter medications containing acetaminophen is common. The potential for errors and adverse events associated with unintentional misuse of these products is substantial, particularly among heavy users of acetaminophen and those with limited literacy.
Health Literacy and Learning Program, Division of General Internal Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA. mswolf@northwestern.edu
Michael S
MS
Wolf
Jennifer
J
King
Kara
K
Jacobson
Lorenzo
L
Di Francesco
Stacy Cooper
SC
Bailey
Rebecca
R
Mullen
Danielle
D
McCarthy
Marina
M
Serper
Terry C
TC
Davis
Ruth M
RM
Parker
D000082:Acetaminophen / Q000009:adverse effects*; D000328:Adult; D000368:Aged; D018712:Analgesics, Non-Narcotic / Q000009:adverse effects*; D056486:Chemical and Drug Induced Liver Injury / Q000453:epidemiology / Q000209:etiology*; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D004338:Drug Combinations; D004348:Drug Labeling; D062787:Drug Overdose; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D020380:Needs Assessment; D004366:Nonprescription Drugs / Q000009:adverse effects*; D015995:Prevalence; D018570:Risk Assessment; D055815:Young Adult
D018712:Analgesics, Non-Narcotic; D004338:Drug Combinations; D004366:Nonprescription Drugs; D000082:Acetaminophen