Taking essential amino acids, particularly branched-chain amino acids, may cause some adverse side effects, such as exhaustion and loss of motor coordination, states WebMD. The use of this supplement has also been associated with lung failure and increased mortality in patients diagnosed with amyotrophic lateral sclerosis.
The human body is unable to synthesize essential amino acids and must derive these vital dietary components from foods and supplements. When administered intravenously by a health care provider, branched-chain amino acids are considered to be likely safe, notes WebMD.
Branched-chain amino acids are possibly safe when properly taken orally. These substances must be used with caution prior or during activities involving motor skills, such as driving. Increased intake of branched-chain amino acids may also lead to convulsions and a decline in physical and mental functions.