NAD+: research, side effects and dosage in studies
In short
NAD+ is a coenzyme made by the body's own cells, not a peptide. Human studies have mostly used oral precursors, and there are no outcome trials of NAD+ infusions for ageing or wellness [1]. There is no authorised medicine containing NAD+ in the EU [7]regulator.
- NAD+ is offered as infusions and injections, and "boosting" it is marketed as anti-ageing [1] [3]B. We know of no published human study of NAD+ injected under the skin or into muscle.
- The precursors NR and NMN raised blood NAD levels, but effects on function and metabolism were mixed and often null [1].
- Infused NAD+ left the blood quickly, and during infusions people had nausea, a faster heart rate and chest pressure [2]A [3]B.
- One randomised heart trial gave NAD+ into a vein in hospital, but it concerned heart failure, not wellness [10]A.
- There is no authorised medicine containing NAD+ in the EU [7]regulator, and Fimea warns against injectable products bought online [8]regulator.
What is NAD+?
NAD+ (nicotinamide adenine dinucleotide) is a helper molecule, or coenzyme, that many cellular enzymes need. It is not a peptide. It takes part in DNA repair, cell metabolism and immune function, among other things [3]B.
NAD+ levels in the body decline with age, which is why "boosting" it is marketed as anti-ageing [1].
It is important to separate two things. The first is NAD+ itself, given as an infusion into a vein or as an injection. The second is the NAD+ precursors nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), usually taken by mouth, from which the body makes NAD+ [1]. Results from trials of precursors cannot be transferred to NAD+ infusions, because the substances differ in uptake and metabolism [3]B. All substances: Peptides A-Z.
Evidence at a glance
Each cell gives the kind of study and its source. The letter is the evidence level, not the result.
| Claimed effect | Humans | Animals | Cells |
|---|---|---|---|
| Higher NAD levels (oral precursors) | NR and NMN raised levels in several randomised trials [1] [4, 6]A | - | - |
| Ageing and wellness | Precursors: mixed and often null effects; no outcome trials of NAD+ infusions [1] | - | - |
| Insulin sensitivity | NMN for 10 weeks increased muscle insulin sensitivity in women with prediabetes [5]A | - | - |
| Heart failure | NAD+ into a vein for 7 days, 180 patients: pumping function improved at one month, no significant difference in cardiac events [10]A | - | - |
| NAD+ in blood after infusion | Level did not rise for two hours; infused NAD+ was removed quickly [2]A | - | - |
| Safety | Gut symptoms, faster heart rate and chest pressure during infusion [3]B; precursors generally well tolerated [1] | - | - |
"-" = no such study is known.
What is NAD+ studied for?
NAD+ and its precursors are studied for ageing, metabolism and a few diseases. None of these is an approved use in the EU [7]regulator.
- Ageing and wellness: a systematic review found 33 human studies, 28 of them randomised, nearly all with precursors [1].
- Metabolism: NMN and insulin sensitivity in women with prediabetes [5]A.
- Parkinson's disease: a safety trial of high-dose NR [6]A.
- Heart failure: NAD+ into a vein in hospital on top of standard treatment [10]A.
Claims online. Clinics and wellness settings increasingly provide NAD+ infusions, despite limited evaluation of their safety and effectiveness [3]B. According to the review, none of the eligible outcome trials gave NAD+ itself into a vein or muscle for ageing or wellness [1].
How does NAD+ work?
NAD+ is a helper for many enzymes in cellular energy metabolism, DNA repair and immune function [3]B. The idea is that NAD+, which declines with age, could be topped up, but according to the review higher NAD levels have not consistently shown up in function or metabolism [1].
According to the pilot study, NAD+ given into a vein is broken down by enzymes in the blood and removed from plasma quickly [2]A.
Has NAD+ been studied in humans?
The precursors have been studied a lot in humans, NAD+ itself little. For NAD+ given into a vein there is a small randomised pilot study (8 given NAD+, 3 given saline), a retrospective set of records and one randomised heart trial [2]A [3]B [10]A.
Precursors by mouth
- Review (2026). NR and NMN consistently raised NAD-related compounds in blood and cells and were generally well tolerated over weeks to months. Effects on functional, metabolic and vascular outcomes were mixed and often null [1].
- NR in healthy adults (2018). In a crossover trial with two six-week periods, NR was well tolerated in healthy middle-aged and older adults and stimulated NAD+ metabolism [4]A.
- NMN in prediabetes (2021). In a 10-week trial, NMN increased muscle insulin sensitivity in postmenopausal women with prediabetes and overweight or obesity [5]A.
- NR in Parkinson's disease (2023). In 20 patients, high-dose NR raised blood NAD+ up to five-fold over four weeks [6]A.
NAD+ into a vein
- Pilot study (2019). NAD+ was given as a six-hour infusion. Blood NAD+ and its breakdown products did not change for the first two hours, meaning the infused NAD+ was removed from plasma rapidly and completely [2]A.
- Commercial infusion service (2026). In a retrospective review of records, clients received either NAD+ or NR infusions on four consecutive days. Because of symptoms in the NAD+ group, its infusions took 97 minutes on average, compared with 37 minutes for NR. Metabolic changes were variable, and the study was not randomised [3]B.
- Heart failure (2026). In a single-hospital randomised, placebo-controlled trial in China, 180 people with ischaemic cardiomyopathy received NAD+ or placebo into a vein for seven days on top of standard drug treatment. At one month heart pumping function (LVEF) was 45.4% in the NAD+ group and 42.4% with placebo. Cardiac and cerebrovascular events over six months (14.6% and 24.7%) did not differ significantly [10]A.
In summary, precursors clearly affect NAD levels, but benefit for ageing or wellness has not been shown [1]. The only randomised NAD+ infusion trial covered on this page concerned heart patients in hospital, not wellness use [10]A.
Who studies NAD+?
The precursors have been studied in several randomised trials, such as the NR-SAFE trial in Parkinson's disease [4, 5, 6]A. The heart trial was done in one Chinese university hospital [10]A. Seven of the authors of the commercial infusion data were employed by the company that gave the infusions (Restore Hyperwellness) [3]B.
Who wrote this page: the editorial team
This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims were checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.
How long does NAD+ stay in the body?
NAD+ given into a vein does not stay in the blood for long. In the pilot study, blood NAD+ did not rise during the first two hours of the infusion, meaning infused NAD+ left the blood quickly. The breakdown products suggested that enzymes in the blood split NAD+. At six hours, NAD+ and methylnicotinamide were excreted in the urine [2]A.
NR taken by mouth raised blood NAD+ up to five-fold over four weeks in people with Parkinson's disease [6]A.
What are the side effects of NAD+?
NAD+ given into a vein caused symptoms during the infusion in all NAD+ clients in the retrospective data. The precursors were generally well tolerated in studies [1] [3]B.
What users report. In the Reddit accounts we compiled (not research), 47 of 87 people (54%) reported some harm, most often: fatigue or crash (16, 18%), flushing or heat (7, 8%) and nausea or stomach upset (7, 8%). People tend to post when something goes wrong, so this share does not tell how common harms are. The figures mix injected NAD+ and oral precursors (NMN, NR). Split by route, the groups were too small for figures, so for them there are quotes only. The harms in detail: NAD+ user experiences.
NAD+ infusions
In the retrospective data, people receiving NAD+ reported moderate to severe gastrointestinal symptoms, increased heart rate and chest pressure during the infusion. Symptoms resolved when the infusion ended. HDL cholesterol fell in the NAD+ group over 30 days of follow-up [3]B.
Precursors
According to the review, NR and NMN were generally well tolerated over weeks to months [1]. In NR-SAFE there were no moderate or severe adverse events, but serum homocysteine rose slightly at first [6]A. Long-term safety was not studied in these trials.
Risks in products bought online
According to Fimea, impurities such as endotoxins in injectable products bought online can cause serious harm to health [8]regulator. More: Side effects and safety.
Interactions and who lacks data
Interactions with other medicines have not been studied. In the heart trial NAD+ was given in hospital on top of standard heart medication [10]A, but this says nothing about interactions in home use. There are no data for pregnancy, breastfeeding or children.
What speaks against it and what is unknown
Higher NAD levels have not meant benefit: according to the review, effects on function, metabolism and blood vessels were mixed and often null [1].
Contrary evidence
- Infused NAD+ was removed from plasma quickly and did not raise the blood level for two hours [2]A.
- In the infusion data, metabolic changes were variable, and HDL cholesterol fell in the NAD+ group [3]B.
- In the heart trial, cardiac events and hospital stays did not differ significantly from placebo [10]A.
What the evidence does not support
- "An NAD+ drip slows ageing": there are no outcome trials of NAD+ infusions for ageing or wellness [1].
- "NR and NMN trials prove that NAD+ injections work": precursor results cannot be transferred to infusions [1] [3]B.
- "NAD+ is a peptide": it is not, it is a coenzyme [3]B.
It is not known what amount given into a vein is effective or safe over a longer period, and long-term safety has not been studied [3]B [10]A.
NAD+ dosage in studies
NAD+ has no approved dosage, because there is no authorised medicine containing NAD+ in the EU [7]regulator. Below are the amounts used in studies. They are not recommendations.
| Study | Who | Dose and route | Duration |
|---|---|---|---|
| Heart failure (2026) | 180 patients, randomised to NAD+ or placebo | NAD+ 10 mg a day into a vein | 7 days [10]A |
| Pilot study (2019) | 11 healthy men aged 30-55 (8 NAD+, 3 saline) | NAD+ 750 mg into a vein (about 3 µmol/min) | one 6-hour infusion [2]A |
| Infusion service (2026) | clients of a commercial service (6 NAD+, 8 NR) | NAD+ or NR 500 mg into a vein once a day | 4 consecutive days [3]B |
| NR-SAFE (2023), precursor | 20 people with Parkinson's disease (10 given NR) | NR 1,500 mg by mouth twice a day | 4 weeks [6]A |
What the numbers do not tell you. The amounts differed widely, and in the heart trial NAD+ was given in hospital on top of standard treatment [10]A. Oral precursor amounts cannot be compared with NAD+ given into a vein [1]. More: NAD+ doses in studies. The calculator only converts units, and its result is not dosing guidance.
NAD+ vs NR and NMN: what is the difference?
NR and NMN are NAD+ precursors from which the body makes NAD+. They are usually taken by mouth, whereas NAD+ is given into a vein or by injection [1].
- Evidence: the precursors have several randomised trials [1] [4, 5, 6]A; NAD+ itself mainly blood-level and tolerability data plus one heart trial [2]A [3]B [10]A.
- Tolerability: the precursors were generally well tolerated [1], NAD+ infusions caused symptoms during the infusion [3]B.
- Transferability: precursor results cannot be transferred to NAD+ infusions [3]B.
NMN has its own page: NMN.
Is NAD+ legal in Finland?
There is no authorised medicine containing NAD+ in the EU, and NAD+ is not named in the Finnish medicines list [7, 9]regulator.
- Marketing authorisation. The EMA data (15 Sep 2026) contain no product whose active substance is NAD+, NR or NMN [7]regulator.
- Medicines list. NAD+, NR and NMN are not named in Fimea's medicines list (230/2025) [9]regulator. The list is not exhaustive: a substance can still be a medicine if it meets the definition in the Medicines Act.
- Fimea warning, 29 June 2026. The warning concerns injectable peptides bought online, and NAD+ is not a peptide. It does state, however, that a product injected through the skin may be a medicine in Finland and that medicines should be bought only from legal sources [8]regulator.
- Import. Ordering medicines from outside the EU is covered on Peptides and the law in Finland.
This is not legal advice. Disclaimer.
How is an NAD+ product assessed?
You cannot be sure what a product sold for injection contains. According to Fimea, an unauthorised product sold online may contain a different substance than the label says, and a "for research use only" label means the product is not intended for humans [8]regulator.
A seller's own certificate of analysis (COA) does not by itself show that NAD+ sold for injection is pure, sterile or free of endotoxin [8]regulator. More: How to read a COA and check a test result.
FAQ
Is NAD+ a peptide?
No. It is a coenzyme made by the body's cells and needed by many enzymes [3]B.
Is there evidence that NAD+ infusions help?
Not for ageing or wellness. According to the review, no eligible outcome trial gave NAD+ itself into a vein or muscle [1]. One hospital trial in heart patients has been done [10]A.
What is the difference between NAD+ and NR or NMN?
NR and NMN are precursors taken by mouth. Their trial results cannot be transferred to NAD+ infusions [1] [3]B.
Do NR and NMN raise NAD levels?
Yes, in trials they did, but effects on function and metabolism were mixed [1] [6]A.
What side effects have been reported with NAD+ infusions?
Gastrointestinal symptoms, increased heart rate and chest pressure during the infusion. HDL cholesterol fell over 30 days of follow-up [3]B.
How much NAD+ was given in studies?
Studies gave 10 mg a day [10]A, 500 mg a day [3]B or 750 mg as one six-hour infusion [2]A into a vein. This is not dosing guidance: dosage in studies.
Is NAD+ an authorised medicine in the EU?
No. The EMA data contain no medicine with NAD+ [7]regulator.
What do users themselves report about NAD+?
In the Reddit accounts of 87 people we compiled (not research), 46 (53%) reported some benefit and 47 (54%) some harm. The accounts are self-selected and prove neither that it works nor that it is safe: NAD+ user experiences.
Read the research yourself: sources
Every source opens the original publication or the regulator's page. The level shows what the source itself reports.
- Gallagher C, Emmanuel OO, et al. NAD+ supplementation for anti-aging and wellness: A PRISMA-guided systematic review of preclinical and clinical evidence. Ageing Res Rev. 2026;116:103057. PMID 41655607 (review)
- Grant R, Berg J, Mestayer 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;11:257. PMID 31572171 A
- Reyna K, Heinzen G, Patel N, 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;7:1652582. PMID 41704678 B
- Martens CR, Denman BA, Mazzo MR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9:1286. PMID 29599478 A
- Yoshino M, Yoshino J, Kayser BD, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;372:1224-1229. PMID 33888596 A
- Berven H, Kverneng S, Sheard E, et al. NR-SAFE: a randomized, double-blind safety trial of high dose nicotinamide riboside in Parkinson's disease. Nat Commun. 2023;14:7793. PMID 38016950 A
- European Medicines Agency. Medicine data (centrally authorised medicines, data set of 15 Sep 2026): no product with NAD+, nicotinamide riboside or nicotinamide mononucleotide as active substance. EMA regulator
- Fimea. Fimea varoittaa: älä käytä verkosta ostettuja pistettäviä peptidejä / Fimea warns: do not use injectable peptides purchased online. 29 Jun 2026. Fimea regulator
- Finland. Lääkeluettelo (Fimea medicines list), 230/2025, annex 1. Finlex regulator
- Yu X, Xu J, Cao J, et al. Effect of Nicotinamide Adenine Dinucleotide on Heart Failure Caused by Ischemic Cardiomyopathy: A Randomized, Placebo-Controlled Trial. Am J Cardiovasc Drugs. 2026;26(1):97-106. PMID 40954388 A
Research sources checked 9-13 Oct 2026. Regulator and registry sources checked 15 Sep to 13 Oct 2026.
Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.
Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.