Hi I had gone through your question and understand your concern. See , protein shakes are LIKELY SAFE for most children and adults when taken by mouth appropriately. High doses can cause some side effects such as increased bowel movements, nausea, thirst, bloating, cramps, reduced appetite, tiredness (fatigue), and headache. Long term effect: Diets high in protein are often high in saturated fat. This increases your risk of developing heart disease, diabetes and other obesity-related chronic conditions. In addition, if you rely on protein shakes as meal replacements as well as for intense protein loading after exercise, you may become deficient in vitamins and minerals that other foods provide, such as vitamin C. I hope this information was of help. Thank you.