Phenylalanine is an essential amino acid. The body uses it to build proteins and to make tyrosine, dopamine, and norepinephrine. These neurotransmitters influence mood, focus, and mental energy.
Many take it for mood balance and mental sharpness. L-phenylalanine is the natural form, while DL-phenylalanine mixes both mirror-image variants. Some also use it for skin health or joint comfort, though those uses are less consistently backed by evidence.
Absorption is often better on an empty stomach, but taking it with food can ease digestive upset. Typical doses run from 500 mg to 2000 mg per day, depending on the form and individual needs.
Avoid phenylalanine if you have phenylketonuria (PKU) or take MAO inhibitors. It may also interact with certain antipsychotic medications and levodopa. Pregnant or nursing individuals should check with a healthcare provider before use.