This systematic review examines the use of Google Trends in healthcare research, evaluating its methodology, validation, and limitations. The study identified 70 articles that utilized Google Trends, which increased sevenfold from 2009 to 2013. Articles were classified into four topic domains: infectious diseases, mental health and substance use, other non-communicable diseases, and general population behavior. The majority of studies (93%) presented positive findings, suggesting a potential publication bias. Only 7% of articles provided clear documentation for reproducible search strategies, and only 67% provided a rationale for their search inputs. Among surveillance studies, 92% validated their findings against reference data sources, and 80% had correlation statistics ≥0.70. The review highlights the need for improved documentation and transparency to enhance the reproducibility and reliability of Google Trends-based research. A checklist is proposed to guide future studies in documenting their methods and rationale. Despite the potential of Google Trends, significant variability and limitations in study quality and reliability remain, necessitating further research and collaboration between researchers and Google Inc.This systematic review examines the use of Google Trends in healthcare research, evaluating its methodology, validation, and limitations. The study identified 70 articles that utilized Google Trends, which increased sevenfold from 2009 to 2013. Articles were classified into four topic domains: infectious diseases, mental health and substance use, other non-communicable diseases, and general population behavior. The majority of studies (93%) presented positive findings, suggesting a potential publication bias. Only 7% of articles provided clear documentation for reproducible search strategies, and only 67% provided a rationale for their search inputs. Among surveillance studies, 92% validated their findings against reference data sources, and 80% had correlation statistics ≥0.70. The review highlights the need for improved documentation and transparency to enhance the reproducibility and reliability of Google Trends-based research. A checklist is proposed to guide future studies in documenting their methods and rationale. Despite the potential of Google Trends, significant variability and limitations in study quality and reliability remain, necessitating further research and collaboration between researchers and Google Inc.