Reflux esophagitis is classified into grades A, B, C, and D according to the severity of the condition, primarily based on the extent of damage to the esophageal mucosa. Grade C reflux esophagitis, in particular, is considered when up to 75% of the circumferential esophageal mucosa is damaged, which is relatively severe. Further progression can lead to ulcers or even severe damage to the entire esophageal mucosa. Therefore, Grade C reflux esophagitis is considered to be quite serious.