AIM: To report the prevalence and sociodemographic characteristics of complementary medicine (CM) use by Australian and American adults living with gastrointestinal (GI) disorders. METHOD: Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, Medline, Pubmed, Scopus and Web of Science were searched for studies published in English language between 1 January 2008 and 8 April 2018. Additionally, a Google Scholar search and risk of bias assessment were conducted. RESULTS: Twelve (five American and seven Australian) studies, involving 53,991 adults were included. Data were extracted from studies reporting CM use by both specific populations with medically diagnosed GI disorders and the general population with self-reported GI disorders. CM use ranged from 23.6% to 44% (American) and 27.2% to 58% (Australian) by adults with medically diagnosed GI disorders. Whilst CM use was higher amongst females, with higher incomes and education levels. The prevalence of CM use by those with self-reported GI disorders varied from 0.31% to 80%. Herbal, probiotic supplements and mind-body practices were the most prevalent CMs used. The risk of bias assessment identified weaknesses in the external validity, principally related to poor study design. CONCLUSIONS: There is a substantial use of CMs by American and Australian adults with GI disorders. Females with higher education and income are predominant users. There is a need to conduct up-to-date and well-designed prevalence and sociodemographic studies. Additionally, future studies should consider including health literacy and medicines disclosure scales in order to better understand CM use by this population.