The Role of Dispensing Device and Label Warnings on Dosing for Sunscreen Application: A Randomized Trial

Drug manufacturers are expected to provide labeling information needed to yield safe and effective product use. However, it is not clear that consumers dose sunscreen, an over-the-counter drug, appropriately; in fact, existing evidence suggests underdosing as a common phenomenon. The objective of this study was to evaluate the effect of dispensing device and labeling on self-administered doses of sunscreen in young adults. To investigate those effects, a 2 × 2 factorial laboratory experiment crossing dispensing device (two levels) with labeling treatment (two levels) was conducted. Participants applied sunscreen from each of the four treatments; dosing concentration, measured in mg/cm², served as the response variable. Participants (n = 94) were recruited on the campuses of Michigan State University (East Lansing, MI) and California Polytechnic State University (San Luis Obispo, CA). Each participant applied sunscreen from each unique treatment to sites on their arms and legs (four applications). Postapplication, a survey was completed to characterize demographics, risk perception, and sunscreen use patterns. Results indicate participants applied approximately 30% less sunscreen from the pump bottles than the squeeze bottles (difference estimate of 0.3059 mg/cm², standard error = 0.0607, p < .0001); there was no evidence of a difference based on label treatments. Post hoc recognition tests indicated only 55% of participants were able to recognize the two experimental labels they had viewed immediately following sunscreen application. Sunscreen application density was directly related to level of worry regarding skin cancer and frequency of sunscreen use (α = .05). Our results suggest the dispensing device used to deliver sunscreen impacts the dosage amount consumers apply.