Natural Language Processing (NLP) is unique to several other fields because it facilitates human-machine interaction by enabling machines to comprehend human language. This interaction is important as it changes the lifestyle of humans due to its diverse applications in machine translation, email spam detection, information extraction, text summarization, medicine, and question-answering. The significance in medicine is in terms of clinical documentation, disease diagnostics, clinical research, chatbots for patient-facing interfaces, medical transcription and dictation, and clinical coding. This article provides a review of the NLP applications in the medical field in accordance with the research works that were conducted specifically on the application, the challenges faced by healthcare professionals and consumers after the influence of the internet era, a review of the available NLP approaches, a review of the NLP tasks specific to the medical field, and overall, the importance of further development of NLP models that improve healthcare.