Vitamin PP is a vitamin, also known as niacin, which is an essential nutrient and a water-soluble vitamin. Vitamin PP can be converted into niacinamide in the body, which is a component of coenzyme I and coenzyme II, involved in the metabolism of energy in the body, and has the effect of vasodilator. It can treat many diseases, such as headache, migraine, tinnitus, etc. If niacin is lacking, it can lead to pellagra and mange, which clinically manifests as dermatitis, lingual inflammation, diarrhea, fatigue and weakness, and poor memory and other symptoms. Vitamin PP existing drugs are divided into two kinds of tablets and injections, niacin tablets can prevent and treat niacin deficiency, such as pellagra. Niacin injection, on the other hand, has the ability to dilate blood vessels, relieve the symptoms of vasospasm, and improve local blood supply. Clinically, niacin injection is used for the treatment of angina pectoris, and the angina pectoris symptoms will be relieved in most patients. Niacin, if taken in excess, will lead to vasodilatation, and long-term use of large quantities may have damage to the liver, it is recommended that patients supplement under the guidance of a doctor to avoid the adverse consequences of overdose.