Adjunctive testing with viscous substances or larger water volumes should be used routinely as it improves the accuracy of achalasia diagnosis. Chronic opiate use can mimic achalasia. The timed barium swallow remains the best test for assessments of disease severity and prognostication, but the functional lumen-imaging probe, a newer tool which measures esophagogastric junction distensibility using impedance planimetry, is emerging as a potentially more powerful tool for these purposes. Functional esophagogastric junction outflow obstruction is possibly part of the achalasia spectrum. By addressing the potential pitfalls described, and through routine and standardized use of the diagnostic tools mentioned herein, the accuracy of diagnosis, severity assessment, and prognostication of achalasia can be improved.