The Internet of Things (IoT) devices have become popular in recent year. All devices connect network and communicate each other. Therefore all devices become smart. They are used for some systems such as e-Health, e-Energy, e-Home, smart city, smart car etc. IoT device collect data for systems in order to analyze data and give right decision. Thus, attackers attack IoT systems. This paper gives an introduction to IoT healthcare systems and applications, the related security and privacy challenges. This paper tends to analyze the security threats in different layers of the loT, and give recommendation owing to provide security and privacy.