What's the Difference Between Types of Niacin?

Types of Niacin Differ in How They’re Released

Niacin- Supervitamin for Heart Health. Credit: www.wolfsonintegrativecardiology.com / Google Images

How much do you know about the types of niacin available to treat high cholesterol? If you're like many people, using niacin (vitamin B3, nicotinic acid) supplements to lower cholesterol levels may be helpful for you.  

Nicotinic acid is a form of niacin that your doctor may recommend for lowering your cholesterol. Typically given in high doses, it can raise your HDL ("good" cholesterol) while lowering your LDL ("bad" cholesterol) and triglycerides (a type of fat found throughout your body).

Nicotinic acid is mostly available without a prescription (over the counter, or OTC).

  • When buying OTC nicotinic acid to lower your cholesterol, avoid the forms called niacinamide and inositol. Why? Because they have little or no cholesterol-lowering effect.

Nicotinic acid is available in immediate-release, sustained-release, and extended-release forms. These products work in the same way to lower your cholesterol, differing only in how long they take to release nicotinic acid into your body.

Immediate-Release Nicotinic Acid

Immediate-release (IR) nicotinic acid, also known as "fast-release" nicotinic acid, goes into your blood as soon as you take it. Because the whole dose goes into your blood at the same time, IR nicotinic acid is also the form that causes the majority of niacin-induced side effects such as flushing, warmth, and itching.

Some bottles of nicotinic acid may not state if they contain an “immediate-release” or a “sustained-release” (see below) product.

If the label doesn't say which form of nicotinic acid is in the bottle, it's safe to assume that it's an IR product.

Sustained-Release Nicotinic Acid

Sustained-release (SR) nicotinic acid, also known as "timed-release" nicotinic acid, is designed to release nicotinic acid into your body over a period of time instead of all at once.

If you take an SR nicotinic acid product, you may experience niacin-induced side effects, but they usually won't be as uncomfortable as you'd feel if you were taking an IR product.

You need to know that the SR form of nicotinic acid takes the longest of the three forms to leave your body completely. That means that it stays in your body longer than the IR or ER form. For this reason, people taking SR nicotinic acid have an increased risk of liver toxicity, which is rare in those taking IR and ER products. To reduce your risk of liver toxicity, you may want to take an ER form of nicotinic acid instead of an SR form.

Extended-Release Nicotinic Acid

This type of nicotinic acid can be obtained with a prescription from your doctor under the trade name Niaspan. (Slo-Niacin, an OTC controlled-release product, may be less expensive.)

Extended-release (ER) nicotinic acid fits somewhere in between the IR and SR forms of nicotinic acid. Its release into your body is a little slower than with the IR form, but it's faster than with the SR form.

Side effects still may occur, but again, they're not as severe as with the IR form. Additionally, there are no problems of liver toxicity associated with this form of nicotinic acid. 

A Word of Caution

Even if you're buying nicotinic acid over the counter rather than with a prescription, don't think of it as "only a supplement." it's still a form of medication, despite the fact that another name for it is "vitamin B3." Be sure to get your doctor's okay before you start taking it, and report any severe side effects to your doctor right away.


“Niacin and cholesterol.” University of California, Berkeley-Berkeley Wellness (2011).

Pieper JA. "Understanding niacin formulations." Am J Manag Care. 2002; 8(12):S308-S3014.

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