What are the most severe symptoms of acid reflux or gerd?

Problems : The most severe symptoms of GERD would be pneumonia from reflux going in to the lungs, or massive bleeding from severe esophageal ulceration. Over the longer term, a stricture of the esophagus or the development of esophageal cancer are also quite bad. Fortunately, these are all uncommon. Unfortunately, they are not predictable for an individual. Hope this helps!