Aim <p>This study aims to identify the long-term side effects documented across life-threatening diseases. As people are projected to live longer with multiple illnesses and their associated long-term side effects, this research is crucial. Yet, this area of research remains largely unexplored, making this study a pioneering effort.</p> Subject and methods <p>This comprehensive scoping review, conducted in July 2023, adhered to the PRISMA-ScR guidelines. Five databases, including published literature from 2019 to 2023, were searched using life-threatening diseases and long-term side effects as search terms. This study ensures a comprehensive understanding of the topic by including cancer, cardiovascular diseases, chronic obstructive respiratory disease, kidney diseases, and neurodegenerative diseases.</p> Results <p>This review encompassed 114 studies on cancer, chronic obstructive respiratory disease, cardiovascular diseases, kidney diseases, and neurodegenerative diseases. The top ten reported long-term side effects for patients with life-threatening diseases were pain, fatigue, dyspnea, depression/sadness, cognitive problems, constipation/diarrhea, anxiety, impaired mobility, nausea/vomiting, and insomnia. Interestingly, pain, cognitive problems, and depression/sadness were reported across all disease groups, underscoring their universal impact.</p> Conclusion <p>This review highlights the complexity and variability in the representation and prevalence of long-term side effects across different disease groups. It also provides valuable insights for clinical practice and research, potentially guiding the development of more effective rehabilitation strategies.</p>