Amino acid supplements can cause side effects, including headaches, nausea, and digestive discomfort. Additionally, since they impact blood glucose levels, they can interact with some medications.Vangipurapu, J., Stancáková, A., Smith, U., Kuusisto, J., & Laakso, M. (2019). Nine Amino Acids Are Associated With Decreased Insulin Secretion and Elevated Glucose Levels in a 7.4-Year Follow-up Study of 5,181 Finnish Men. Diabetes, 68(6), 1353–1358. If you take any medications, especially insulin or other diabetes medication, you should talk to your doctor before taking amino acid supplements. You should also avoid amino acid supplements before or after surgery unless directed by a physician.