TwinLab L-Arginine is an amino acid. One hard gelatin capsule contains 500 mg of free form, crystalline pure L-Arginine.Twinlab L-Arginine capsules are easier to swallow and assimilate.Well tolerated by the most highly allergic individuals. No tablet binders, coatings or colorings. Free of the most common allergens such as corn, soy, yeast, rice, barley, wheat, lactose (milk sugars) and all milk, citrus, fish, and egg products. No added flavorings, sugars, preservatives or salicylates.