The medical information sharing involves information collection, information storage, and sharing of this information. Protection to medical information against malicious attacks is an important concern due to its storage on remote cloud. In current online question answering system for health-related issues, extraction of medical knowledge from the clamorous question- answers pair is a challenge. To overcome these challenges, medical knowledge extraction scheme for cloudlet based healthcare system is proposed. The proposed and developed medical knowledge extraction (MKE) scheme finds valid remedial Triples from clamorous question-answer (Q-A) pairs and evaluate the reliability along with doctor's proficiency using truth discovery method the modified number theory research unit algorithm (NTRU) and collaborative intrusion detection system (CIDS) is used to avoid and detect malicious attacks. The response time of the proposed system is 6 to 8 seconds which results in a substantial reduction in time and cost for the end-user. © 2019 Inderscience Enterprises Ltd.