Head to head
Niacin against Nicotinamide
Two forms of vitamin B3 that are routinely treated as interchangeable and are not. One has been tested against hard cardiovascular outcomes in more than 29,000 people and prevented no events; the other cut new non-melanoma skin cancers by 23 percent over 12 months in a phase 3 trial and does not cause flushing.
Column A
NiacinNicotinic acid, niacin, the acid form of vitamin B3
The only compound in the NAD pathway ever tested against hard cardiovascular outcomes, in 25,673 patients in HPS2-THRIVE and 3,414 in AIM-HIGH. It moved every lipid it was supposed to move and prevented no events in either trial, and HPS2-THRIVE found excess serious adverse events including infection and bleeding.
Column B
NicotinamideNicotinamide, the amide form of vitamin B3
In the ONTRAC phase 3 trial, 500 mg twice daily cut the rate of new non-melanoma skin cancers by 23 percent over 12 months in 386 high-risk patients, with no benefit once the tablets stopped. The identical trial in 158 organ transplant recipients found nothing, and no trial has ever tested nicotinamide against an ageing outcome.
The mistake this page exists to correct
Niacin and nicotinamide are sold as the same vitamin and are frequently swapped in supplement write-ups and in NAD marketing. They behave differently. Niacin lowers LDL and raises HDL and causes flushing; nicotinamide does neither. Niacin is the only NAD pathway compound ever tested against cardiovascular events, in 25,673 patients in HPS2-THRIVE and 3,414 in AIM-HIGH, and it prevented none while HPS2-THRIVE found excess serious adverse events including infection and bleeding. Nicotinamide's strongest result is in skin cancer prevention and disappeared once the tablets stopped. Neither result transfers to the other molecule.
Side by side, on the facts we can check
| Attribute | Niacin | Nicotinamide |
|---|---|---|
| Category | Longevity | Longevity |
| FDA status | Extended-release nicotinic acid is an FDA-approved prescription lipid drug in the United States, though its clinical use collapsed after AIM-HIGH and HPS2-THRIVE. Lower-dose nicotinic acid is also sold over the counter as a supplement. The extended-release niacin with laropiprant combination used in HPS2-THRIVE was withdrawn worldwide after the trial reported. | Not an approved drug for skin cancer prevention in the United States. It is a recognised form of the vitamin niacin, sold over the counter, and included in multivitamins and topical cosmetics. The ONTRAC dose is an over-the-counter dose used off-label. |
| Half-life | Under an hour for immediate-release nicotinic acid. Extended-release formulations were built specifically to stretch that out and blunt the flush, and the dose is not interchangeable between forms. | About 4 hours in plasma, which is why the skin cancer trials dosed it twice a day rather than once. |
| Molecular weight | 123.1 Da | 122.1 Da |
| Mechanism | Nicotinic acid enters NAD synthesis through the Preiss-Handler pathway rather than the NAMPT salvage route, which is why it is a genuinely potent NAD booster and why a 2026 human study proposed that gut bacterial conversion of NR and NMN into nicotinic acid may be how those two expensive precursors work at all. Its lipid effects are separate and act mainly through inhibition of adipocyte lipolysis and hepatic diacylglycerol acyltransferase, reducing free fatty acid flux to the liver and VLDL output. The flush is a third, distinct mechanism: nicotinic acid activates the receptor GPR109A on immune cells in skin, releasing prostaglandins D2 and E2 that dilate cutaneous vessels. Mouse knockout work established each link in that chain. The laropiprant in HPS2-THRIVE was a prostaglandin D2 receptor antagonist added to block exactly this, which worked for the flush and did nothing for the outcomes. | Nicotinamide enters NAD synthesis through the salvage pathway. NAMPT, nicotinamide phosphoribosyltransferase, converts it to NMN, and NMNAT enzymes convert NMN to NAD. NAMPT is the rate-limiting step, which is the structural reason more nicotinamide does not translate linearly into more NAD: the bottleneck is enzymatic, not substrate supply. Separately, nicotinamide is the product released when sirtuins, PARPs and CD38 consume NAD, and it inhibits sirtuin deacetylation by binding a conserved pocket adjacent to NAD and switching the enzyme toward base-exchange chemistry rather than deacetylation. In skin, the proposed cancer-prevention mechanism is different again and does not depend on systemic NAD at all: nicotinamide supports PARP-dependent repair of UV-induced DNA damage and reduces UV-induced cutaneous immunosuppression. |
| Human studies cited | 5 | 4 |
| Legal status, US | FDA-approved prescription lipid drug, also sold over the counter as a supplement | Sold as a supplement |
Frequently asked questions
What is the difference between Niacin and Nicotinamide?
Niacin: The only compound in the NAD pathway ever tested against hard cardiovascular outcomes, in 25,673 patients in HPS2-THRIVE and 3,414 in AIM-HIGH. It moved every lipid it was supposed to move and prevented no events in either trial, and HPS2-THRIVE found excess serious adverse events including infection and bleeding. Nicotinamide: In the ONTRAC phase 3 trial, 500 mg twice daily cut the rate of new non-melanoma skin cancers by 23 percent over 12 months in 386 high-risk patients, with no benefit once the tablets stopped. The identical trial in 158 organ transplant recipients found nothing, and no trial has ever tested nicotinamide against an ageing outcome.
Which has stronger research evidence, Niacin or Nicotinamide?
This database does not grade compounds. It counts what was run in people: 5 of the 6 studies cited on the Niacin profile were human work, against 4 of 5 for Nicotinamide. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are Niacin and Nicotinamide FDA-approved?
Niacin: Extended-release nicotinic acid is an FDA-approved prescription lipid drug in the United States, though its clinical use collapsed after AIM-HIGH and HPS2-THRIVE. Lower-dose nicotinic acid is also sold over the counter as a supplement. The extended-release niacin with laropiprant combination used in HPS2-THRIVE was withdrawn worldwide after the trial reported.. Nicotinamide: Not an approved drug for skin cancer prevention in the United States. It is a recognised form of the vitamin niacin, sold over the counter, and included in multivitamins and topical cosmetics. The ONTRAC dose is an over-the-counter dose used off-label..
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.