Background: Fear appeals are commonly used in health communication to reduce risk. It is not clear, however, whether familiarity with a health topic can lessen the threat intended. The use of unregulated dietary supplements among young adults is one such area that needs study. Purpose: The study examined the effect of fear appeals on self-protective behavior when college students were informed of the risks of consuming the dietary supplement creatine. It focused on students' responses to fear appeals that varied depending on their familiarity with the product. Methods: Students were assigned to one of 3 groups based on familiarity with creatine. A total of 121 college students viewed advertisements depicting creatine consumption side effects, followed by the main questionnaire including perceived risk, attitudes, and behavioral intention measures. Results: Fear appeal messages were most effective for those least familiar with creatine. Discussion: Familiarity based on previous experience is a factor that must be considered when presenting threatening health information. Translation to Health Education Practice: Health educators and practitioners should inform young adults about risks and proper consumption of dietary supplements before they develop a strong disposition toward the product without accurate knowledge of proper dose and potential side effects.