Nicotinic acid (niacin) is a form of vitamin B3 found naturally in meat, eggs and dairy products. It is also available as an over-the-counter supplement as vitamin B3 or niacin. Niacin is sometimes used in the treatment of high cholesterol (hypercholesterolemia). Because of this, it is often referred to as a cholesterol-reducing drug, along with statins, fibrates and bile acid resins.

There are two main forms of vitamin B3: nicotinic acid (niacin) and nicotinamide (niacinamide). When these substances are taken in low doses for nutritional purposes, they are virtually identical. However, when taken in the high doses necessary for the treatment of high cholesterol, the effects of these two substances vary. Nicotinamide (niacinamide) in high doses is generally used for the prevention or early treatment of type 1 (child onset) diabetes and for the reduction of symptoms associated with osteoarthritis. In comparison, nicotinic acid (niacin) is preferred for high dose use in the treatment of high cholesterol. Nicotinamide should not be used as a substitute for nicotinic acid as it does not lower cholesterol levels.

A special form of niacin (inositol hexaniacinate or IHN) may also be used in the treatment of high cholesterol, as well as certain peripheral venous disorders (e.g., Raynaud syndrome, claudication).

While statins are considered the first line of defense for treating high cholesterol, nicotinic acid has shown an ability to increase blood levels of HDLs (or “good” cholesterol). Nicotinic acid is also highly effective in lowering blood levels of triglycerides and lipoprotein “a”. Lipoprotein “a” – abbreviated Lp(a) – is a component of cholesterol that is associated with increased risk of heart disease. Nicotinic acid may be prescribed in addition to other cholesterol-reducing medications to further reduce triglyceride levels and increase HDL levels.

According to the National Institutes of Health, nicotinic acid may reduce LDL-cholesterol levels by 10 to 20 percent and triglycerides by 20 to 50 percent. In addition, nicotinic acid may raise HDL-cholesterol by 15 to 35 percent.

While nicotinic acid is available over-the-counter, physicians often prefer to prescribe it in time-released pills. Side effects of large doses of nicotinic acid can be intense and may include flushing, palpitations and nausea. Patients are often directed to slowly build up to the high doses of nicotinic acid needed to treat high cholesterol. Even with proper buildup, as many as 50 percent of patients find the side effects of this medication too difficult to tolerate. Because of the potentially intense side effects, patients should never begin taking large doses of niacin supplements without the supervision of a physician. Recent research has revealed an interaction with immune cells as the mechanism that causes the flushing or hot flashes. Researchers may be able to use this information to moderate nicotinic acid therapy to minimize the flushing response.

Various amounts of niacin may also be prescribed for a number of other conditions, including:

• Cancer
• Diabetes
• Prolonged diarrhea or fever
• Hartnup disease (a rare, inherited metabolic disorder)
• Persistent infection
• Stomach ulcer or intestinal problems
• Liver or pancreas disease
• Mouth or throat sores
• Hyperthyroidism (overactive thyroid)
• Chronic stress 
• Surgical removal of stomach.

Patients should not begin taking niacin for these or other conditions without consulting their physician.

Claims may be made that niacin is an effective treatment for other ailments, including acne, leprosy, motion sickness, poor circulation, mental disorders, leprosy, alcoholism and the unwanted effects of drug abuse. However, none of these claims have been scientifically proven. Recent studies suggest that the use of niacin may be helpful in reducing the risk of heart attack. Its main therapeutic use for the cardiovascular system remains to reduce blood cholesterol levels, and a reduction in blood cholesterol levels has been proven to reduce the risk of heart disease and heart-related death.