Guide
nicotinamide riboside (NR) side effects
Across the largest safety trials, nicotinamide riboside produced mostly mild side effects — occasional nausea and muscle soreness — at rates similar to placebo, with no reports of the flushing associated with niacin and no rise in LDL cholesterol when taken alone.
Across the largest controlled trials, nicotinamide riboside's side effects have been mostly mild — occasional nausea and muscle soreness — at rates similar to placebo. Unlike niacin, it hasn't been linked to flushing in these trials, and taken alone it hasn't raised LDL cholesterol the way a related combination product did in one trial.
What shows up most often
In the largest safety trial — 140 adults given placebo, 100 mg, 300 mg, or 1,000 mg of NR a day for 8 weeks — 61 of the 140 participants reported at least one adverse event, all similar in type, rate and severity across every group including placebo. The mild side effects flagged as possibly related to the supplement itself were nausea, muscle pain or soreness, leg pain, and a sore back; there were no serious adverse events and no reports of flushing at any dose (PMID 31278280). A separate 6-week crossover trial reported a similar mild profile — nausea, leg cramps and increased bruising during NR — while headache, rash, fainting and drowsiness turned up during the placebo phase of the same trial (PMID 29599478).
Flushing: the comparison to niacin
Niacin (nicotinic acid) is well known for causing a warm, reddening skin flush at doses above about 50 mg, and nicotinamide riboside is often marketed on the promise that it doesn't share that effect. The trial evidence backs that up so far: the 140-person, 8-week trial reported zero flushing cases across every dose up to 1,000 mg/day, and in the separate crossover trial, flushing was actually reported more often during the placebo phase (2 cases) than during NR treatment (1 case) — the opposite of what you'd expect if NR itself caused it (PMID 31278280, PMID 29599478). See what is nicotinamide riboside (NR)? A plain guide for the mechanism researchers think explains the difference.
Cholesterol: a distinction worth knowing
Nicotinamide riboside taken by itself, at doses up to 1,000 mg/day for 8 weeks, did not raise LDL cholesterol or plasma homocysteine in the trial that measured both directly (PMID 31278280). That same paper notes a separate trial of a combination product containing NR plus pterostilbene did find a dose- and time-dependent rise in LDL cholesterol — an effect attributed to the combination, not established for nicotinamide riboside on its own (PMID 29184669). If you're comparing products, that's a reason to check whether NR is standing alone or blended with something else on the label — more in how to choose a good nicotinamide riboside (NR).
At higher doses
The highest sustained dose tested in a controlled trial was 2,000 mg a day (1,000 mg twice daily) for 12 weeks, in 40 obese men. No serious adverse events occurred, and safety blood work stayed within normal range throughout (PMID 29992272) — the highest tested dose wasn't associated with a worse safety profile than the lower ones, at least over that 12-week period.
Questions people ask
What are the side effects of nicotinamide riboside?
Most commonly reported as possibly related: nausea, muscle soreness or pain, leg pain, and occasional bruising or leg cramps. These have been mild across every trial reviewed here, with no serious adverse events reported at doses up to 2,000 mg/day.
Does nicotinamide riboside make you sleepy?
Drowsiness was reported in one trial, but during the placebo phase, not during NR treatment — there's no trial evidence linking nicotinamide riboside itself to drowsiness (PMID 29599478).
What is really known about the effects of nicotinamide riboside?
On safety specifically: it's been well tolerated across every controlled trial reviewed here, at doses up to 2,000 mg/day for up to 12 weeks, with side effect rates similar to placebo and no flushing. See nicotinamide riboside (NR) benefits: what the research does and doesn't show for what's known about whether it does anything beyond raising NAD+.
Does nicotinamide riboside cause nausea?
Nausea has been reported as a possible side effect in more than one trial, at rates that appeared in both NR and placebo groups. It's one of the more commonly mentioned mild effects, not a rare or unusual one.
Related reading: who should not take nicotinamide riboside (NR)?, nicotinamide riboside (NR) and medications: what to check, and how much nicotinamide riboside (NR) should you take a day?
Sources
- Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults A 2019 randomized, placebo-controlled trial of 140 adults found nicotinamide riboside raised blood NAD+ dose-dependently at 100-1,000 mg/day over 8 weeks with no reports of flushing and no rise in LDL cholesterol or homocysteine, unlike the other forms of vitamin B3.
- Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD(+) in healthy middle-aged and older adults A 2018 crossover trial's discussion explains that niacin's flushing reaction comes from binding a specific skin receptor (GPR109A) that nicotinamide riboside isn't expected to activate, and found flushing reports were, if anything, more common on placebo than on NR.
- A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects A 2018 trial of 40 obese men given 2,000 mg/day of NR for 12 weeks found no improvement in insulin sensitivity, glucose metabolism, or body composition compared with placebo, though it was safe and well tolerated.
- Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD(+) levels in humans safely and sustainably: a randomized, double-blind, placebo-controlled study A 2017 trial of a nicotinamide-riboside-and-pterostilbene combination product in 120 older adults found dose-dependent NAD+ increases (about 40% and 90% at two doses) over 8 weeks with no serious adverse events — a combination-product result, not one isolating NR alone, and no clinical outcome beyond NAD+ was measured.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.