Poisoning Interventions

Warning Labels


Warning labels are usually colorful stickers (with a picture of a scowling face and its protruding tongue) placed on containers of hazardous substances ostensibly in order to warn children to stay away. In the United States, these stickers are commonly referred to as Mr. Yuk ( Mr.

Yuk ) and were developed by the National Poison Center in Pittsburgh. The efficacy of this intervention can be measured by observing changes in poisonings before and after the introduction of warning labels to a certain population, as well as observing children’s behavior toward the warning labels.

Review of warning label studies:


Vernberg et al., 1984

Study design and target population

Randomized controlled trial.

Children age 12 to 30 months (n=20).


Mr Yuk warning labels and educational instruction (5 minutes in each of two sessions) for intervention group only.


Touching containers with Mr. Yuk labels.


Experimental group showed a significantly increased preference for Mr. Yuk-labeled containers compared to control group (p=0.02).

Study quality and conclusions

Small sample size; developmental difference in age range studied.

Mr. Yuk labels appear to attract children.

No evidence that intervention was understood by subjects.


Fergusson et al., 1982

Study design and target population

Non-equivalent control group design.

Families with 2-year-olds participating in the Christchurch Child Development Study, Christchurch, NZ (n=1156).


Mr Yuk warning labels and instructional information for intervention families only.

No intervention for control group.


Hospital records of childhood poisonings among the two groups.


No significant difference in subsequent poisonings between intervention and control group.

Poisonings were not affected by compliance to program.

Study quality and conclusions

Good study to determine effect of Mr. Yuk stickers.

No evidence supporting reduction in poisonings from intervention.

Intervention may actually increase risk of poisoning because of colorful sticker on medicine container.

Summary of warning label studies

Of the two studies examining the effectiveness of warning labels, one actually showed an increase in children’s handling of the labeled medicine. The other study showed no effect of the intervention, but did hint that the warning labels may increase the risk of poisoning. It is clear from the studies to date, warning stickers are not a good deterrent for children.

Recommendations on warning label programs

At this time, these colorful warning stickers cannot be advocated for use as a deterrent for children. This is especially true for toddlers, who may not understand the meaning of the sticker’s image (even though older children may benefit from its appearance). The usefulness of the label appears to be only in the phone number for the local Poison Control Center.

Recommendations for future research

An appropriate approach to examine whether a different type of warning sticker (say, a black and white design; or perhaps something not as cartoonish) is effective in deterring children from handling medicine is a randomized controlled trial. The study by Vernberg and colleagues11

  was a good attempt at such a study. Such studies should examine children of different age categories, keeping in mind the developmental differences between, for example, a toddler and a 4-year old.