The main method currently used in healthcare IoT systems for performing computations with sensor data is cloud computing. Cloud computing presents a possible issue the transfer of data to the cloud and back to the user device creates large delays. These delays can cause problems for IoT tasks that require real-time responses either for patients or healthcare providers. This article provides a review of fog computing in healthcare IoT systems. Fog computing, an alternative to cloud computing, was first introduced by Cisco and is centered on moving the cloud capabilities closer to the user. Fog computing does so by using edge devices for storage, communication, and computation. The article provides a performance evaluation of fog computing in healthcare IoT and enumerates some of the challenges facing the technology.