Better health through warning labels

Each year, millions of Americans suffer from ‘adverse drug events’ caused by the inappropriate use of prescription drugs. This doesn’t necessarily mean they purposefully took drugs when they knew they shouldn’t. Often people simply misread or misunderstand warning labels, leading to incorrect dosing or dangerous drug interactions. What can be done about this?

In an effort to prevent these drug reactions, many pharmacies add colorful warning stickers on medicine vials that say things such as ‘do not consume alcohol while taking this medication’. However, as prescription warning labels (PWLs) are not regulated, each pharmacy is free to choose their own wording and design. There have been studies to see what kind of phrasing is most easily understood, but Laura Bix and her colleagues from the University of Michigan and Kansas State University wondered whether a bigger problem might be that people don’t notice the stickers in the first place.

Because elderly people are at greater risk for adverse drug effects, largely because they take more drugs, the researchers used two groups of volunteers, fifteen people aged 20-29 and seventeen people aged 51-77. Each participant was shown five prescription vials with PWLs in different colors. Eye tracking indicated when and for how long each person looked at the main white label, the colored PWL, and the vial’s cap. Next, the subjects were asked to remember which PWLs they had seen on the vials.

Actual vial used in this study:

a. The three label zones of interest: cap, standard white pharmacy label and prescription warning label (PWL). 

(Inset: Five color contrasts of PWLs used in this study) 

b. Flattened, scaled drawing.

doi:info:doi/10.1371/journal.pone.0038819.g001

Younger people were more likely to spend time looking at the PWL during the eye tracking exercise. They were also better at recalling exactly which PWLs they had seen. However, even young people spent more time looking at the main label than at the PWLs, and were only able to correctly identify the PWLs they’d seen two thirds of the time.

These data suggest that the kinds of PWLs most often used by pharmacies are simply not attracting enough attention, especially among older people. This is true even when the PWLs are in bright colors with bold lettering. In contrast, all the subjects did spend time looking at the plain white label on the front. The authors suggest that people expect to find relevant information on the front of the vial, and may not bother to look around the sides or back. If so, pharmacies may do better to print PWLs on the main label rather than on separate stickers.