FROM BUILT LEAN:
Generally, most of the complications associated with whey protein intake have to do with digestive issues, such as gas, bloating, headaches, cramps and fatigue. None of these are generally considered life-threatening, more so than annoying complications.
Most of the literature has shown that if you’re experiencing any of have these symptoms, they are most likely due to either the lactose (found more in Whey Protein Concentrate) or sweeteners used more so than the whey protein itself. With that said, there are different methods of whey production, such as ion-exchanged that can influence how well your body can utilize the protein, leading to improper digestion of the whey itself.
The biggest fear often expressed about whey protein intake is that too much protein is “bad for the kidneys.” Research though has shown this is not true at all in healthy individuals. For those with known kidney disease, high protein diets can exacerbate pre-existing conditions. Healthy individuals, without any underlying or unknown kidney disease have nothing to worry about with higher intakes of protein.
What does occur with higher protein intakes is your body adapts to the increase in protein by increasing glomerular filtration rates (which means more fluid passes by your kidneys and there’s an increase in urine production).