Over-the-Counter forms of Niacin (Vitamin B3)

Types of Over-the-Counter Preparations

No-flush niacin (inositol hexaniacinate)

  • Also called “zero-flush” or “flush-free”
  • Does not contain niacin, but gets broken down to niacin in the body but at much lower levels than other forms of niacin
  • Effects on lipids are not as well studied as other forms of niacin
  • Patients do not have flushing with inositol hexaniacinate
  • Most expensive form of over the counter niacin
  • Doses of 2000-3000 mg daily are needed to be effective and then only works well in about half of patients so close monitoring of effect is needed


  • Also called “controlled-release” or “timed-release”
  • Cause less flushing than immediate release preparations
  • Several formulations have been shown to be more likely to cause liver
  • Toxicity than the immediate release
  • Examples: Slo-Niacin and Enduracin

Immediate release

  • Also called “crystalline” or “plain” niacin
  • Absorbed within 1 hour of ingestion
  • Used safely for > 40 years
  • Least expensive form of niacin
  • Usually more flushing than above forms and must take 3 times a day; flushing can be reduced by taking after meals, taking an 81 mg aspirin 30 minutes prior to niacin, and avoiding hot drinks, spicy foods, and alcohol with niacin