This dissertation investigates the consequences of supply chain disruptions in pharmaceutical supply chains. Across different studies, I examine various impacts of pharmaceutical supply chain disruptions on buyer’s behavior, medication errors, and market share. In Chapter 1, coauthored with Anita Carson, Erin Fox, and Rena Conti, we demonstrate the stockpiling behaviors of buyers during the early phase of the COVID-19 pandemic. Leveraging a quasi-experimental design on IQVIA’s National Sales Perspectives™ data, we show that the sales volume of essential medicines related to U.S. hospital-based COVID-19 treatment concentrated only for the first two months of the pandemic. After these two months, the sales volume of drugs for COVID-19 treatment decreases significantly despite a nationwide increase in COVID-19-related hospitalizations. In Chapter 2, coauthored with Anita Carson and Rena Conti, we examine the impact of a hurricane that decimated the factories of major producers of heparin, an important drug used frequently in hospitals. Using a natural experiment, we find that the hurricane-related pharmaceutical supply chain disruption increased medication error rates of heparin. In addition, we find significant spillover effects. The supply chain disruption increased the medication error rates of a substitute drug. In Chapter 3, coauthored with Anita Carson and Rena Conti, we study how long it takes to recover the market share after the supply chain disruptions using a new metric we propose, Time to Recover Market Share. We explore the differential effects by the brand type of products, the competition level in markets, and the duration of the supply disruptions. With the extensive global supply chain disruptions that we are facing today, understanding their potential consequences is significant. This dissertation advances our understanding of the different impacts of supply chain disruptions and provides practical implications for supply chain members to build resilient supply chains and minimize the effects of supply chain disruptions.