This paper examines whether and how the introduction of peer-to-peer (P2P) lending platforms affects opioid-related mortality, one of the most severe public health crises in the United States with over 150 daily overdose deaths. The theoretical relationship is ambiguous: while improved credit access may alleviate economic stress and reduce opioid intake motivated by financial distress, it could potentially enable opioid prescribing by providing additional financial resources. Exploiting the staggered introduction of Lending Club across U.S. states as a quasi-natural experiment, we find that P2P lending entry leads to a reduction of 17 opioid-related deaths per million population. The effect operates through improved psychological well-being, as evidenced by reduced work intensity, decreased mental health-related mortality, and lower suicide rates. Cross-sectional analyses reveal stronger effects in areas with limited banking presence, higher household leverage, and lower sunlight exposure, consistent with P2P lending being particularly beneficial where financial constraints and psychological vulnerability are more severe.