Purpose: Hyperhidrosis (i.e. excessive sweating) is diagnosed from patient medical history and physical examination. In addition, focal sweat measurements can substantiate the hyperhidrosis diagnosis. Likewise, the impact of living with hyperhidrosis can be assessed with patient-reported outcome measures. However, no consensus exists on how to diagnose hyperhidrosis, how to quantify the disease, or how to measure the impact hyperhidrosis has on patients. Therefore, the objective of this review was to summarize the literature on diagnostic criteria, focal sweat measurement methods, and patient-reported outcome measures of hyperhidrosis. Methods: A literature search of Cochrane Library, Embase, and PubMed was conducted. Studies that included and aimed at developing or validating hyperhidrosis diagnostic criteria, focal sweat measurement methods, or patient-reported outcome measures for individuals with hyperhidrosis were eligible for inclusion. The methodological quality of diagnostic accuracy studies about focal sweat measurement methods was determined using the Quality Assessment of Diagnostic Accuracy Studies-2. Results: Overall, 33 studies were included. We identified two sets of hyperhidrosis diagnostic criteria, one scale for assessment of severity of hyperhidrosis sweating, four focal sweat measurement methods, and 15 patient-reported outcome measures. Conclusion: The algorithm for diagnosing hyperhidrosis and focal sweat measurement methods needs validation in large cohorts. Most patient-reported outcome measures for hyperhidrosis are not adequately validated. A potential solution is to develop a core outcome set that can standardize outcomes reported in clinical trials.