ObjectiveTo investigate the following among patients with phrenic neuropathy: (1) occurrences of water immersion activity-induced dyspnea; (2) clinical, electrophysiologic, sonographic, and pulmonary function test abnormalities; and (3) frequency of documented counseling regarding the risks of water immersion activities.MethodsWe identified all patients with test-confirmed phrenic neuropathy seen from January 1, 2000, to December 31, 2018, at Mayo Clinic.ResultsOf 535 patients with phrenic neuropathy, documentation of dyspnea with water activities was identified in 4% (22/535). The risks of water immersion were only documented in patients having experienced this problem. The majority had isolated phrenic neuritis or neuralgic amyotrophy syndrome (77.3%), mean age was 55 years (range 31-79), and most patients were men (81.9%). Patients had right-sided (45.5%) or bilateral (54.5%) phrenic neuropathy. None had isolated left phrenic involvement. Near-fatal drowning occurred in 18.2% (4/22), with persons needing assistance to be rescued from the water, following diving into water. Dyspnea with water immersion was the only symptom in 4.5% (1/22) and the presenting respiratory symptom in 36.4% (8/22). A range of electrophysiologic, sonographic, and pulmonary function test abnormalities including mild abnormalities were seen and not found to be significantly different from those in patients in whom water-induced dyspnea was not recorded.ConclusionRespiratory distress with water immersion activities is a serious complication of phrenic neuropathies. Physician-documented counseling is lacking. Isolated phrenic neuritis, neuralgic amyotrophy, and right-sided and bilateral phrenic involvement are most commonly implicated, but the range of severity and testing abnormalities suggest that all patients with neuralgic amyotrophy or phrenic neuropathy should be warned especially about diving into water.