NAD+ Side Effects: What the Research Reports
Cellular Energy & Mitochondrial Research
In a controlled 2019 pilot of intravenous NAD+, a six-hour infusion in eight healthy men produced no adverse events; a 2026 review of clinic records found that NAD+ infusions brought on stomach cramping, nausea, a faster heart rate and chest pressure that stopped as soon as each infusion ended. Placebo-controlled trials of oral NAD+ precursors in up to 140 adults found adverse-event rates similar to placebo. This guide sets out what each study recorded and how NAD+ and the ready-mixed NAD+ Nasal Spray fit a laboratory research setting.
Findings
- During a 6-hour intravenous NAD+ infusion, no adverse events were observed in either the NAD+ or the saline group (Grant et al., 2019).
- In a retrospective clinic review, symptoms during NAD+ infusions ceased immediately when each infusion finished, and liver, kidney, thyroid and inflammation markers did not change significantly over 30 days (Reyna et al., 2026).
- In an 8-week trial of the precursor nicotinamide riboside in 140 adults, 40-45.7% of each active group reported an adverse event against 48.6% on placebo, with no serious events and no flushing (Conze et al., 2019).
- A 2026 systematic review of 33 human intervention studies found oral NAD+ precursors generally well tolerated over weeks to months.
View product →What is NAD+?
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme, a helper molecule that enzymes need to work, present in every living cell. It shuttles electrons in energy metabolism and is consumed by enzymes involved in DNA repair and cell signalling, and its levels fall with age, which is why it is studied in ageing research. It is a nucleotide rather than a peptide, as explained in NAD+ Is Not a Peptide; the wider background is in What Is NAD+? and the research findings in NAD+ Benefits: What the Restoration Research Shows.
What did the intravenous NAD+ studies report?
The 2019 infusion pilot
Eleven healthy men aged 30-55 were randomised to a six-hour intravenous NAD+ infusion (eight men) or saline (three men). The study’s main finding was metabolic: NAD+ was rapidly and completely cleared from the plasma for at least the first two hours, then its breakdown products appeared in blood and urine. No adverse events were observed in either group during the infusion. Four liver-related values shifted slightly in the NAD+ group (bilirubin rose from 9.3 to 12.0 µmol/L, and the enzymes GGT, LD and AST fell), and the authors considered none of the changes clinically significant (Grant et al., Front Aging Neurosci, 2019).
The 2026 clinic review
A retrospective review of records from a commercial wellness clinic compared six people who received NAD+ infusions on four consecutive days with eight who received nicotinamide riboside (NR) infusions. Participants set their own infusion rate according to tolerance. All six in the NAD+ group reported moderate to severe abdominal cramping during infusions, along with diarrhoea, nausea, vomiting, a faster heart rate, throat discomfort, congestion and chest pressure. These symptoms ceased as soon as each infusion was completed, and they led participants to slow the drip, so NAD+ infusions averaged 97 minutes against 37 minutes for NR. Blood pressure did not change significantly, and ALT, AST, hsCRP, BUN/creatinine and TSH were unchanged over 30 days (Reyna et al., Front Aging, 2026). The review had no placebo arm, and its authors were employed by the clinic.
What the two studies show together
In both studies, the recorded effects were confined to the infusion itself. In the 2019 pilot the infusion ran slowly over six hours with no adverse events; in the 2026 review, where infusions were shorter, symptoms were common but ended with the infusion and no blood markers moved out of range. A 2026 systematic review found no outcome trials of intravenous or intramuscular NAD+ itself, and treated the 2019 pharmacokinetic pilot as contextual evidence (Gallagher and Emmanuel, Ageing Res Rev, 2026).
What did trials of NAD+ precursors show?
Most controlled human data come from oral precursors, compounds the body converts into NAD+. In a randomised, double-blind, placebo-controlled crossover trial in 30 healthy middle-aged and older adults, six weeks of nicotinamide riboside raised NAD+ metabolism and was well tolerated. Adverse events were mild: five on NR (one each of nausea, flushing, rash, leg cramps and increased bruising) and nine on placebo, with no serious events and no meaningful differences in blood chemistry, kidney or liver markers (Martens et al., Nat Commun, 2018). In an 8-week trial in 140 overweight but otherwise healthy adults, NR raised whole-blood NAD+ by up to 142%; adverse events were similar across all NR groups and placebo, none were serious, all resolved by the end of the study, and there were no reports of flushing (Conze et al., Sci Rep, 2019).
What about the nasal route?
In a 2026 study, NAD promoted the maturation of human olfactory stem cells into smell-sensing neurons, and intranasal NAD restored olfactory function and repaired the olfactory lining in mice with induced loss of smell (Yoo et al., Exp Mol Med, 2026). For intranasal NAD+, the published work to date is laboratory research. The spray format is covered in NAD+ Nasal Spray in Canada.
How does NAD+ compare with related compounds?
NAD+ is often studied alongside glutathione, the cell’s main antioxidant; their roles and human data are compared in NAD+ vs Glutathione, and glutathione’s own safety record is in Glutathione Side Effects.
Why research-grade quality and storage matter
Identity, purity and storage all affect whether laboratory results can be compared with the published work. Vistara Labs supplies NAD+ as a lyophilised vial and as a ready-mixed metered nasal spray. Every product is third-party tested, with certificates on the lab reports page. Mixing is covered in the NAD+ reconstitution guide and stability in How Long Does NAD+ Last?
NAD+ is supplied by Vistara Labs for laboratory research use only. The human studies above were clinical research carried out under medical supervision.
Frequently asked questions
What side effects has NAD+ research reported?
A controlled six-hour intravenous infusion in eight healthy men produced no adverse events. A 2026 clinic review recorded cramping, nausea, a faster heart rate and chest pressure during infusions, which stopped as soon as each infusion ended. Oral precursor trials found adverse-event rates similar to placebo.
What did the NAD+ infusion pilot study show?
In the 2019 study, NAD+ was rapidly cleared from the plasma for the first two hours of a six-hour infusion, no adverse events were observed, and small shifts in liver values were judged not clinically significant.
What did trials of NAD+ precursors show about tolerability?
Placebo-controlled trials of nicotinamide riboside in 30 and 140 adults found it well tolerated, with mild adverse events at rates similar to placebo, no serious events, and no meaningful changes in blood chemistry.
What has research shown about intranasal NAD+?
The published intranasal work is laboratory research. A 2026 study found intranasal NAD restored olfactory function and repaired the olfactory lining in mice with induced loss of smell.
Where can I buy NAD+ in Canada?
Vistara Labs supplies NAD+ as a lyophilised vial and a ready-mixed nasal spray, third-party tested and shipped from within Canada by Canada Post Xpresspost.
Product details from vistaralabs.ca, October 2026. Sources: Grant R et al. A pilot study investigating changes in the human plasma and urine NAD+ metabolome during a 6 hour intravenous infusion of NAD+. Front Aging Neurosci. 2019. PMID 31572171. Reyna K et al. Intravenous infusion of nicotinamide adenine dinucleotide (NAD+) versus nicotinamide riboside (NR): a retrospective tolerability pilot study in a real-world setting. Front Aging. 2026. PMID 41704678. Gallagher C, Emmanuel OO. NAD+ supplementation for anti-aging and wellness: a PRISMA-guided systematic review of preclinical and clinical evidence. Ageing Res Rev. 2026. PMID 41655607. Martens CR et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018. PMID 29599478. Conze D et al. 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. Sci Rep. 2019. PMID 31278280. Yoo SH et al. Therapeutic effect of intranasal nicotinamide adenine dinucleotide in the restoration of olfactory dysfunction. Exp Mol Med. 2026. PMID 42380286.
More on this: Buy NAD+ in Canada: A Researcher’s Guide.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
References
Human NAD+ work is largely pharmacology and tolerability rather than clinical outcomes. A 2026 systematic review reports no eligible clinical-outcome trial of intravenous or intramuscular NAD+ itself for anti-ageing or wellness.
- NAD⁺ supplementation for anti-aging and wellness: A PRISMA-guided systematic review of preclinical and clinical evidencePRISMA systematic review; 113 intervention studies including 33 human studies. Reports no eligible clinical-outcome trial of intravenous or intramuscular NAD+ itself for anti-ageing or wellness.
- A Pilot Study Investigating Changes in the Human Plasma and Urine NAD+ Metabolome During a 6 Hour Intravenous Infusion of NADHuman pilot pharmacology study; plasma and urine NAD+ metabolome during a 6-hour intravenous infusion. Not an efficacy trial.
- Intravenous infusion of nicotinamide adenine dinucleotide (NAD(+)) versus nicotinamide riboside (NR): a retrospective tolerability pilot study in a real-world settingRetrospective tolerability pilot comparing four days of intravenous NAD+ with intravenous nicotinamide riboside in a real-world setting.
- Oral LNAD+ rapidly elevates whole blood intracellular NAD and metabolic flux without elevating plasma NAD: evidence from a randomized controlled trialRandomised controlled trial of a specific modified ORAL NAD+ formulation; clinical outcomes exploratory and formulation-specific.
Links open the study record on PubMed so the source can be checked directly. Listing a study is not a claim that its findings apply to any other use, product or route of administration. Research use only.
