Niacin goes by several names: nicotinic acid, vitamin B3, and sometimes just “the flushing vitamin” because of its most notorious side effect. Your body needs it to make NAD and NADP, coenzymes involved in over 400 reactions including energy metabolism, DNA repair, and cell signalling [1].

Most people get enough niacin from food. The recommended daily intake is about 16 mg for men and 14 mg for women, easily met through meat, fish, nuts, and fortified cereals. But the doses used medicinally, particularly for cholesterol management, are far higher, typically 1,000 to 3,000 mg daily. At those levels, niacin becomes a different beast entirely.

I’ve gone through the clinical evidence for niacin’s various claimed benefits. Some hold up reasonably well. Others are more complicated than supplement marketing would have you believe.

Types of niacin supplements

Walk into a health food shop and you’ll find three forms:

Nicotinic acid is niacin in its original chemical form. It’s the one that lowers blood lipids, but it’s also the one that turns your face and chest red. The flushing can be quite dramatic, especially when you first start taking it.

Nicotinamide (also called niacinamide) is a derivative that doesn’t cause flushing. The trade-off? It also doesn’t lower cholesterol. It’s mainly useful for addressing actual niacin deficiency or for topical skin applications.

Inositol hexanicotinate (sometimes marketed as “flush-free niacin”) is supposed to deliver niacin’s lipid benefits without the flushing. The reality is less impressive. Studies show it doesn’t absorb as well, and the cholesterol-lowering effects are weaker or absent [2]. If you’re taking it specifically for cardiovascular benefits, you may be wasting your money.

Benefits with reasonable evidence

1. Lowering cholesterol

This is niacin’s main claim to fame, and the evidence here is solid, at least for the effect itself. At doses of 1,500 to 3,000 mg daily, niacin raises HDL cholesterol by 15-35% and lowers LDL cholesterol by 5-25%. It also reduces triglycerides by 20-50% [3].

The mechanism is interesting. Niacin doesn’t increase HDL production. Instead, it inhibits an enzyme in liver cells that breaks down HDL, so more of it stays circulating in your blood [4].

Here’s the catch, though. A major trial called AIM-HIGH tested whether adding niacin to statin therapy improved actual health outcomes, not just cholesterol numbers. The study enrolled 3,414 patients with established cardiovascular disease who were already on statins. Adding extended-release niacin (1,500 to 2,000 mg daily) did improve their HDL and LDL numbers significantly. But there was no difference in heart attacks, strokes, hospitalisations, or deaths between the niacin group and placebo group [5].

The trial was stopped early because niacin clearly wasn’t helping. If anything, the niacin group had slightly more strokes, though the difference wasn’t statistically significant.

What does this mean? Niacin genuinely does change your cholesterol numbers. But changing the numbers doesn’t necessarily translate to living longer or avoiding heart attacks, at least not when added to modern statin therapy. The “raise your HDL” theory of cardiovascular prevention has taken a beating in recent years.

2. Reducing cardiovascular disease risk

Despite the AIM-HIGH results, older evidence suggests niacin might have cardiovascular benefits when used differently.

A systematic review and meta-regression analysis covering 11 studies and 9,959 participants found that niacin, either alone or combined with other lipid-lowering drugs, did reduce cardiovascular events [6]. The effect on stroke specifically was less clear.

The authors suggested that niacin’s benefits might not come from cholesterol changes alone. Niacin also affects inflammatory markers like C-reactive protein and phospholipase A, and it increases adiponectin, a hormone with protective effects on blood vessels.

My honest take: the picture is muddled. Niacin probably has some cardiovascular benefit, but it’s not as straightforward as “raise your HDL, protect your heart.” The benefit seems largest when niacin is used instead of statins, not alongside them. Given that statins have much stronger evidence for reducing heart attacks and deaths, niacin has largely been relegated to second-line status in clinical practice.

If you’re already on a statin and tolerating it well, adding niacin probably won’t help much. If you can’t tolerate statins, niacin might be worth discussing with your doctor.

Benefits with moderate evidence

3. Osteoarthritis symptoms

This one’s less well-known. Nicotinamide (the non-flushing form) may help with osteoarthritis, the “wear and tear” joint disease that affects nearly half of people over their lifetime [7].

A 12-week double-blind trial of 72 patients with osteoarthritis found that oral nicotinamide improved overall joint impact scores, increased joint flexibility, and reduced the need for anti-inflammatory medications compared to placebo [8].

The mechanism isn’t entirely clear, but nicotinamide might support cartilage cell metabolism and have mild anti-inflammatory effects.

A few caveats: this was a small study from 1996, and there haven’t been many follow-up trials. I wouldn’t call the evidence strong, but it’s intriguing. If you have osteoarthritis and are looking for something to try alongside conventional treatment, nicotinamide has a reasonable safety profile at the doses used (around 3,000 mg daily in divided doses).

For more on joint health supplements, see our article on health foods for osteoarthritis.

4. Skin photoageing

Here’s the application most people haven’t heard about. Topical nicotinamide (applied as a cream or serum) appears to improve signs of facial ageing from sun exposure.

A 12-week double-blind study of 50 women with photoaged facial skin found that a nicotinamide-containing moisturiser reduced fine lines and wrinkles, increased skin elasticity, and improved hyperpigmentation and redness compared to the vehicle alone [9].

The proposed mechanism involves nicotinamide boosting collagen and glycosaminoglycan production while reducing protein glycation, one of the processes that makes skin stiffer with age.

Topical nicotinamide has become quite popular in skincare products, and the evidence, while not overwhelming, does support modest benefits. The flushing issue doesn’t apply when niacin is used topically; nicotinamide creams are generally well tolerated.

For photoaging specifically, the evidence is better for topical use than oral supplementation. Taking niacin pills probably won’t do much for your wrinkles.

Side effects and safety concerns

The famous niacin flush

If you take nicotinic acid (the lipid-lowering form), you will almost certainly experience flushing at some point. It typically starts 15-30 minutes after taking a dose and involves redness, warmth, and tingling in the face, neck, and chest. Some people describe it as feeling like a sunburn or an intense blush.

The flushing is caused by prostaglandin-mediated vasodilation. It’s not dangerous, but it’s unpleasant enough that many people stop taking niacin because of it. The effect tends to decrease over time as your body adapts, usually over 2-4 weeks of regular use.

Taking aspirin 30 minutes before niacin can reduce flushing, as can taking niacin with food. Extended-release formulations cause less flushing than immediate-release, though they have their own problems (more on that below).

Gastrointestinal effects

Nausea, vomiting, diarrhoea, and general stomach upset are common, especially at higher doses. Taking niacin with meals helps.

Serious concerns at high doses

Once you get into therapeutic dosing (multiple grams per day), the risks increase:

Liver damage is the main concern, particularly with sustained-release formulations. Extended-release niacin is gentler on flushing but harder on the liver. The NHS recommends regular liver function monitoring for anyone taking high-dose niacin [10].

Blood sugar elevation is clinically documented. A meta-analysis of 11 cardiovascular studies involving 26,340 participants found that niacin therapy increased the risk of developing diabetes by 34%, regardless of whether it was used alone or with other lipid-lowering drugs [11].

Gout flares can occur because niacin increases uric acid levels. If you have a history of gout or hyperuricaemia, high-dose niacin is probably not for you.

Peptic ulcers may be aggravated.

Vision problems including blurry vision and macular oedema have been reported rarely.

Who should avoid niacin

Pregnant and breastfeeding women should not exceed 35 mg daily
People with liver or kidney disease
People with active peptic ulcers
People with gout or high uric acid
People taking blood pressure medications (niacin can lower blood pressure further)
People with diabetes or prediabetes (niacin worsens glucose tolerance)
People with arrhythmias or unstable angina
Anyone scheduled for surgery in the next two weeks

Drug interactions

Niacin interacts with quite a few medications:

Statins: combining niacin with statins increases the risk of muscle damage (myopathy). The combination was once popular but has fallen out of favour
Bile acid sequestrants (cholestyramine, colestipol): can reduce niacin absorption. Take them several hours apart
Blood pressure medications: additive blood pressure lowering effects
Blood thinners: may enhance anticoagulant effects
Diabetes medications: niacin raises blood sugar, potentially requiring dose adjustments
Nicotine patches: may worsen flushing

The flushing effect is also worsened by alcohol, which dilates blood vessels through the same mechanism.

Practical considerations

If you’re considering niacin supplementation:

For general health: you probably don’t need it. Most people get adequate niacin from food, and deficiency (pellagra) is rare in developed countries.

For cholesterol management: discuss with your doctor first. Niacin’s role has diminished considerably since statins became standard care. It might make sense if you can’t tolerate statins, but the evidence for outcomes (as opposed to just cholesterol numbers) is weaker than for statins.

For skin: topical nicotinamide products are a reasonable option with good tolerability. Look for concentrations around 4-5%.

For joint health: nicotinamide might be worth trying for osteoarthritis, but set realistic expectations. The evidence is preliminary.

Start with low doses and increase gradually to minimise flushing. Take with food. If you experience persistent nausea, abdominal pain, or dark urine (potential signs of liver problems), stop and see a doctor.

References

National Institutes of Health, Office of Dietary Supplements. Niacin Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Niacin-HealthProfessional
Capuzzi DM, et al. Efficacy and safety of an extended-release niacin (Niaspan): a long-term study. Am J Cardiol. 1998;82(12A):74U-81U. PMID: 9915665
NHS. B vitamins and folic acid. nhs.uk/conditions/vitamins-and-minerals/vitamin-b
Zhang LH, et al. Niacin inhibits surface expression of ATP synthase beta chain in HepG2 cells: implications for raising HDL. J Lipid Res. 2008;49(6):1195-1201. PMID: 18316796
AIM-HIGH Investigators. Niacin in patients with low HDL cholesterol levels receiving intensive statin therapy. N Engl J Med. 2011;365(24):2255-2267. PMID: 22085343
Lavigne PM, Bhagwat M. Niacin therapy and the risk of new-onset diabetes: a meta-analysis of randomised controlled trials. Heart. 2013;99(1):52-58. PMID: 23265337
Murphy L, et al. Lifetime risk of symptomatic knee osteoarthritis. Arthritis Rheum. 2008;59(9):1207-1213. PMID: 18759314
Jonas WB, Rapoza CP, Blair WF. The effect of niacinamide on osteoarthritis: a pilot study. Inflamm Res. 1996;45(7):330-334. PMID: 8841834
Bissett DL, et al. Niacinamide: a B vitamin that improves aging facial skin appearance. Dermatol Surg. 2005;31(7 Pt 2):860-865. PMID: 16029679
Mayo Clinic. Niacin (Vitamin B3). mayoclinic.org/drugs-supplements-niacin
Goldie C, et al. Niacin therapy and the risk of new-onset diabetes: a meta-analysis of randomised controlled trials. Heart. 2016;102(3):198-203. PMID: 26370223