Branched-chain amino acids appear to be safe for most people when used for up to 6 months. Some side effects are known to occur, such as fatigue and loss of coordination. Branched-chain amino acids should be used cautiously before or during activities where performance depends on motor coordination, such as driving.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Not enough is known about the use of branched-chain amino acids during pregnancy and breast-feeding. Stay on the safe side and avoid use.
Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease): The use of branched-chain amino acids has been linked with lung failure and higher death rates when used in patients with ALS. If you have ALS, don’t use branched-chain amino acids until more is known.
Branched-chain ketoaciduria: Seizures and severe mental and physical retardation can result if intake of branched-chain amino acids is increased. Don’t use branched-chain amino acids if you have this condition.
Chronic alcoholism: Dietary use of branched-chain amino acids in alcoholics has been associated with liver disease leading to brain damage (hepatic encephalopathy).
Low blood sugar in infants: Intake of one of the branched-chain amino acids, leucine, has been reported to lower blood sugar in infants with a condition called idiopathic hypoglycemia. This term means they have low blood sugar, but the cause is unknown. Some research suggests leucine causes the pancreas to release insulin, and this lowers blood sugar.
Surgery: Branched-chain amino acids might affect blood sugar levels, and this might interfere with blood sugar control during and after surgery. Stop using branched-chain amino acids at least 2 weeks before a scheduled surgery.