Whey protein may cause bloating, gas, and indigestion in some due to its high lactose content.
Whey protein allergies can cause hives, swelling, difficulty breathing, and itching.
Excess protein, including whey, can stress kidneys by making them work harder to process .
Some may get acne from whey protein due to high insulin levels producing more oil.
Overuse of whey supplements can cause nutrient imbalances (high calcium) leading to constipation or kidney stones.