Excessive vitamin C supplementation can cause the following: 1. Most commonly, it causes digestive problems, such as bloating, nausea, vomiting, acid reflux, diarrhea, heartburn and other symptoms of excessive secretion of gastric acid in the upper gastrointestinal tract. Because vitamin C is an acidic vitamin, an overdose of acidic vitamins in the gastrointestinal tract can lead to bloating, abdominal pain, acid reflux, heartburn, etc. 2, too much vitamin C can lead to stones in the urinary system, especially stones formed by calcium carbonate in the urinary system. This is because vitamin C can easily cause calcium carbonate to be deposited in the urinary system, thus leading to the occurrence of stones. 3, too much vitamin C can lead to hemolysis, vitamin C is an ascorbic acid, if taken in excess will lead to hemolytic anemia. 4, if too much vitamin C can also appear rashes, such as localized red papules on the body, all belong to vitamin C supplement overdose.