Do not use if you are pregnant or breastfeeding, or have the genetic metabolic disorder phenylketonuria (PKU). For prolonged use, consult a health care practitioner. Supplemental L-tyrosine may increase blood pressure or lead to difficulty sleeping in some persons. Consult a health care practitioner prior to use if you have hyperthyroidism, Graves’ disease or active melanoma, or if you are taking dopamine, thyroid hormone medication, contraceptives or other psychoactive medications. Discontinue use if you experience nausea, headache, fatigue, heartburn or joint pain.