Misunderstanding of Prescription Drug Warning Labels Among Patients With Low Literacy

Michael S. Wolf; Terry C. Davis; Hugh H. Tilson; Pat F. Bass, III; Ruth M. Parker


Am J Health Syst Pharm. 2006;63(11):1048-1055. 

In This Article

Abstract and Introduction


Purpose: The common causes for misunderstanding prescription drug warning labels (PWLs) among adults with low literacy were studied.
Methods: A total of 74 patients reading at or below the sixth-grade level and receiving care at the primary care clinic at the Louisiana State University Health Sciences Center in Shreveport were recruited to participate in structured interviews. Patients were asked to interpret and comment on eight commonly used warning labels found on prescription medications. Correct interpretation was determined by expert panel review of patients' verbatim responses. Qualitative methods were employed to code responses and generate themes regarding the misunderstanding of these PWLs.
Results: Among this sample of patients with low literacy skills, rates of correct interpretation for the eight warning labels ranged from 0% to 78.7%. With the exception of the most basic label, less than half of all patients were able to provide adequate interpretations of the warning label messages. Five themes were derived to describe the common causes for misunderstanding the labels: single-step versus multiple-step instructions, reading difficulty of text, use of icons, use of color, and message clarity. Labels were at greater risk for being misunderstood if they included multiple instructions, had a greater reading difficulty, included unfamiliar terms, or used confusing icons that were discordant with text messages. Participants also frequently imposed an incorrect meaning on label colors, which led to further confusion.
Conclusion. Patients with low literacy skills demonstrated a lower rate of correct interpretation of the eight most commonly used PWLs than did those with higher literacy skills. Multiple-step instructions, reading difficulty of text, the use of icons, the use of color, and message clarity were the common causes of label misinterpretation.


Nearly half of the adult population in the United States lack the reading and numeracy skills required to process, understand, and act on health information.[1] Forty million U.S. adults are reading at the lowest levels of literacy proficiency and may have profound difficulty understanding health information for their own or a loved one's needs.[2,3] Prior studies have linked low literacy to a poor understanding of one's medical condition and nonadherence to medical instructions.[4,5,6,7]

Individuals with low literacy skills may be at particular risk for misunderstanding information on pharmaceutical drug labels and package inserts, thus misusing these medications.[8,9] Recent concern over patient safety has increased awareness of the poor quality of consumer information describing proper use of medications and associated risks.[10,11] This has led to an expanded interest in the causes of medication-related errors, from a focus on physician or health care system failure to analysis of potential patient errors.[8,9,10,11,12] As health care delivery continues to shift from inpatient to outpatient settings, the burden of quality control over proper medication use will also shift from provider to patient.[1,9,13,14] An alarming trend has already emerged as a result: between 1983 and 1993, there was a ninefold increase in deaths due to outpatient medication errors in the United States.[15] A recent study reported that 28% of emergency department visits are drug related, with over two thirds of these visits deemed preventable and 24% resulting in hospital admission.[16]

The Food and Drug Administration (FDA), along with the American Pharmacists Association, the American Society of Health-System Pharmacists, and the National Association of Boards of Pharmacy (NABP), is directing greater attention to the quality of labels on prescription and nonprescription drugs and accompanying patient educational handouts and package inserts.[17,18,19,20,21,22,23] In 1997, the Keystone Dialogue, initiated by the Department of Health and Human Services and the abovementioned organizations, was charged with developing an action plan for improving medication information and labeling.[24] One of the many recommendations made was to directly involve consumers to ensure that information included on medication labels and package inserts could be properly understood by patients across all literacy levels.

Our research team previously investigated the quality of prescription drug warning labels (PWLs) that appear as stickers placed on the outside of medication bottles.[8] These adhesive labels are widely used and provide important information regarding the safe administration of prescription medications. Failure to heed the warnings or special instructions on these labels could lead to a loss of drug potency or a change in the rate of absorption of the medication. As a consequence, patients may become ill or gain little or no treatment benefit from taking the prescribed drug.[25] For example, many long-acting antihypertensive agents should be swallowed whole, as chewing or crushing them would intensify the dose and could possibly cause acute hypotension.

Our findings revealed very low rates of comprehension of PWLs and that low literacy was a significant independent predictor of an incorrect interpretation of their meaning. In the present study, the causes for misunderstanding text and icons found on eight commonly used PWLs among patients reading at or below the sixth-grade level (low literacy) were explored.