Social media have become increasingly important in risk and crisis situations. However, little is known about which types of social media have greater influence on risk perceptions and behaviors. This study pursues two goals related to this question. The first is to explicate the cognitive mechanism underlying the process through which exposure to risk information on social media shapes people's behavioral intentions. The second is to determine whether exposures to risk information on two different types of social media-content-oriented social media focusing on shared interests versus user-oriented social media focusing on social relationships-have different effects on people's risk perceptions and behavioral intentions. Analyzing survey data from 688 adults from the general population of South Korea in the context of carcinogenic hazards, we found that self-reported content-oriented social media exposure (to risk information) was significantly related to both personal-level and societal-level risk perceptions. In addition, content-oriented social media exposure was associated with behavioral intentions indirectly through risk perceptions. However, user-oriented social media exposure had no impact on risk perceptions and behavioral intentions, either directly or indirectly through risk perceptions.