The aldosterone-to-renin ratio (ARR) is a common screening test for primary aldosteronism in hypertensives. However, patients often use medications that could confound the ARR and, thereby, reduce the interpretability of the test. Since it is not always feasible to stop such medication, several drugs that are supposedly neutral with respect to the ARR have been recommended as alternative treatment. The objective of the present review is to explore whether sufficient evidence exists to justify the recommendations. To this end, we performed a systematic PubMed and Cochrane literature search regarding medications that may influence the ARR. Our review revealed that many commonly prescribed antihypertensives seem to have significant effects on renin, aldosterone, and resulting ARR values. However, the magnitude of these effects is poorly quantifiable with the present level of research. We conclude that several medications can affect the ARR. Not taking this into account could lead to misinterpretation of the ARR. Therefore, standardization of the medications used during ARR measurement is advisable for a reliable and accurate interpretation. Further research is needed to ascertain how to best optimize these medications.