Purpose: Halitosis is an unpleasant breath odor which can be bothersome to individuals. Extra-oral halitosis is a type of halitosis caused by systemic conditions, bloodborne diseases, or pharmaceutical therapy. It is not related to local factors in the oral cavity. This systematic review aimed to identify the medications that can cause extra-oral halitosis. Materials and Methods: This study was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA). We searched online databases and also included hand searching to find relevant articles. Two authors independently performed the screening, data extraction and quality assessment of the included articles using the Cochrane Collaboration assessment tool. Results: Thirty-four studies met the eligibility criteria. The medications which can cause extra-oral halitosis were categorised into 10 groups: acid reducers, aminothiols, anticholinergics, antidepressants, antifungals, antihistamines and steroids, antispasmodics, chemotherapeutic agents, dietary supplements, and organosulfur substances. Conclusion: Pharmaceutical therapy is a potential source of extra-oral halitosis. This finding can help clinicians detect the probable causes of halitosis. Further studies are needed to definitely determine the role of various medications in causing extra-oral halitosis. Keywords: adverse drug events, adverse drug reactions, drug side effects, extra-oral halitosis, halitosis