According to Clinical Correlations, The NYU Langone Online Journal of Medicine, people drink ginger ale when sick because ginger is thought to contain a number of active ingredients that help alleviate nausea and vomiting. Similar use of ginger is documented in records from as early as the first century A.D.
The Clinical Correlations article states that the use of ginger to remedy nausea and vomiting extends beyond Europe and the United States. Indian and Chinese medicine still utilize ginger for this purpose. Scientific studies of ginger's efficacy have produced mixed results. Mass-produced commercial ginger ale is not an effective clinical treatment for nausea and vomiting because it contains only artificial flavoring, not natural ginger extract.