Caustic ingestion in adults is a rare but potentially life-threatening problem. It remains controversial whether endoscopic findings and mortality differ between acid and alkali ingestion. We compared ingestion of these agents and evaluated prediction parameters for survival and complications.Adult patients who presented with caustic ingestion were analyzed from 2005 to 2016. Mucosal injury was graded endoscopically by Zargar's score. Age, gender, intent of ingestion, caustic agents, comorbidities, management, complications, and mortality were examined.Thirty-one patients met inclusion criteria and were divided into acid (n = 10) and alkali group (n = 21). Ingestion of alkali resulted in higher grades (≥III) of esophageal (56% vs 24%, P = .01) and stomach injuries (43% vs 13%, P = .05) and was mostly done with suicidal intent (76% vs 30%, P = .003). Patients in the alkali group received more often surgical interventions, mechanical ventilation and tracheotomy. Overall complications including Zargar's-score ≥ grade III, mediastinitis, and aspiration pneumonia were higher in alkali group but all showed no statistical significance (P = .73). Mortality (acid: 1 (10%), alkali: 4 (19%), P = .52), age, gender, comorbidities, and intensive care management did not differ significantly between the groups. Chronic renal failure and mediastinitis were promising prediction parameters for mortality but did not reach statistical significance. No independent risk factors for the development of esophageal stenosis were identified.Alkaline agents caused a higher mucosal injury severity and were more often used in suicidal intent. Mediastinitis and chronic renal failure might be potential prediction parameters for survival but need to be evaluated in larger studies.