The Internet of Things (IoT) has given rise to numerous security issues that require effective solutions. IoT security patterns have been suggested as an effective approach to address recurrent security design issues. Although several IoT security patterns are proposed in the literature, it remains unclear how they impact the energy consumption and CPU usage of IoT-edge-based applications. We conducted an empirical study using three testbed IoT applications (i.e., smart home, smart city, and healthcare) to shed light on this issue. We evaluated the impact of six IoT security patterns, including Personal Zone Hub, Trusted Communication Partner, Outbound-Only Connection, Blacklist, Whitelist, and Secure Sensor Node, both in pairs and in combination (i.e., all patterns). Specifically, we conducted multiple penetration tests to first assess the pattern’s effectiveness against attacks. Then, we conducted a comprehensive analysis of the energy consumption and CPU usage of the applications with/without the implemented security patterns, aiming to evaluate the potential impact of these patterns on energy efficiency and CPU usage. Our findings demonstrate a statistically significant increase in energy consumption and CPU usage. Based on these findings, we provide guidelines for IoT developers to follow when implementing IoT-edge-based applications.