Excessive protein intake can lead to several potential side effects, including kidney damage due to increased nitrogen waste, dehydration from the body's need for more water to metabolize protein, and digestive issues like constipation or diarrhea. Long-term high protein consumption could also affect bone health, as it may lead to increased calcium excretion. It's important to balance protein intake with other nutrients and to be mindful of overall dietary diversity to mitigate these risks.