Arginine is classified as a semiessential or conditionally essential amino acid , depending on the developmental stage and health status of the individual.  Preterm infants are unable to synthesize or create arginine internally, making the amino acid nutritionally essential for them.  Most healthy people do not need to supplement with arginine because it is a component of all protein-containing foods  and can be synthesized in the body from glutamine via citrulline . 
L-arginine seems to decrease blood pressure. Taking L-arginine along with medications for high blood pressure might cause your blood pressure to go too low.<br /><br />
Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others.