What it is
NAD+, nicotinamide adenine dinucleotide, is not a peptide. It is a dinucleotide coenzyme built from an adenine nucleotide and a nicotinamide nucleotide, and it is a normal metabolite present in every human cell. It appears on this site because it is marketed and sold the same way peptides are, at the same wellness clinics and IV bars, not because it is chemically related to them.
This entry covers direct, exogenous administration of NAD+ itself: intravenous drips, intramuscular or subcutaneous injection, and intranasal spray. It does not cover the oral precursor compounds NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside, sold as Niagen or Tru Niagen), which the body converts into NAD+ through one or two enzymatic steps, or nicotinamide and niacin, further upstream vitamin-form precursors; those are a separate topic with their own, in places much larger, literature. NADH, the reduced form of NAD+, is likewise a distinct molecule, studied separately and by a different route (orally, for chronic fatigue). Vendor and consumer material routinely blurs all of this together under the phrase “NAD booster,” and an “NAD+ injection” sold at a clinic may in fact contain NAD+ itself or may be an NMN or NR product marketed under the same loose language; which one a person was actually given determines which evidence base, if any, applies. NAD+ also appears under its Chinese pharmacopeia name, “Coenzyme I,” in some trial registrations; that is the same molecule, not a different substance.
Mechanism
The underlying biochemistry is well established. NAD+ accepts electrons, becoming NADH, during glycolysis, the citric acid cycle and fatty-acid oxidation, and NADH is re-oxidized back to NAD+ at the mitochondrial electron transport chain to drive ATP synthesis, a cycle continuous in every human cell. NAD+ is also the substrate sirtuin enzymes (SIRT1-7) consume in DNA-damage signaling and metabolic regulation, the substrate PARP enzymes consume during DNA-damage repair, and the substrate CD38 degrades; CD38 activity rises with age and inflammation and is one of the most-cited explanations for why tissue NAD+ falls with age.
A large preclinical literature, mostly using oral precursors rather than NAD+ itself, reports that restoring NAD+ improves mitochondrial function and metabolic markers as animals age. The step from that finding to “raising NAD+ in humans changes aging or disease outcomes” is a hypothesis under study, not an established fact, and a 2026 review states directly that intravenous NAD+ administration “is less well characterized and lacks robust clinical validation” (Pandolfi 2026). A more consequential open question is whether NAD+ given by IV or intranasal route ever reaches the inside of a human cell intact: NAD+ is a relatively large, charged dinucleotide, and whether it crosses cell membranes as itself, is broken down extracellularly with its components re-taken-up as smaller precursors, or acts partly through cell-surface signaling, is not resolved in the literature reviewed. That gap is the premise the entire IV NAD+ industry depends on, and it is addressed further below.
What the human trials found
Direct NAD+ administration has been studied far less than its marketing footprint suggests. A 2026 PRISMA-guided review, searching January 2010 through October 2025, found 113 eligible human and rodent NAD-related intervention studies and stated: “No eligible outcomes trials evaluated intravenous or intramuscular NAD+ itself for anti-aging or wellness indications” (Gallagher & Emmanuel 2026). That is close to a definitive statement of the gap between what is marketed and what has been tested.
The one real exception is a randomized, placebo-controlled trial in a cardiac population, not a wellness one. A single-center Chinese trial (registry ChiCTR2200059169, not ClinicalTrials.gov) randomized 180 adults with ischemic cardiomyopathy and reduced ejection fraction to IV NAD+ 10 mg per day for 7 days, added to guideline-directed heart failure therapy, or placebo. Ejection fraction at one month rose to 45.44 percent with NAD+ against 42.44 percent with placebo, significant but numerically small; no secondary endpoint reached significance on its own, and the authors call for validation in larger, multicenter trials (Yu 2025). This trial has nothing to do with addiction treatment, cognition, fatigue or anti-aging, and generalizing its result to those uses is not supported by the trial itself.
A separate retrospective comparison, drawn from records at a commercial IV-therapy clinic chain, is the clearest documented source for what is often described anecdotally as IV NAD+’s infusion discomfort. Adults received four consecutive days of either 500 mg IV NAD+ or 500 mg IV nicotinamide riboside, with 30-day follow-up. The NAD+ group reported moderate to severe gastrointestinal symptoms, increased heart rate and chest pressure during infusion, versus only minor tingling and mild cramping with NR; NAD+ infusions also took roughly two and a half times longer, averaging 97 minutes against 37 for NR, because the rate had to be slowed for tolerability. Standard liver, kidney and inflammatory labs did not change significantly in either group; HDL cholesterol fell significantly with NAD+ specifically (Reyna 2026). This is real, quantified evidence, but from one clinic network’s retrospective records, not a controlled trial.
The addiction and withdrawal claim, which drives much of the consumer demand for IV NAD+, rests on the thinnest evidence found. The most substantial source is a peer-reviewed but uncontrolled, unblinded, open-label pilot of 50 people with treatment-resistant substance use disorder, given IV NAD+ with enkephalinase-inhibition infusions, reporting large improvements in self-rated craving, anxiety and depression, and clean urine screens partway through treatment; the authors call for larger randomized, placebo-controlled trials (Blum 2022). Beyond that pilot sits a 2014 conference poster on a retrospective review of 60 people given IV NAD+ alongside vitamins and amino acids, not NAD+ alone, and a described 2017 follow-up whose own source calls it an unpublished manuscript still in preparation. No randomized controlled trial of IV NAD+ for opioid or alcohol withdrawal has been located.
For cognition, fatigue and exercise performance by the direct route, the record is close to empty. No controlled trial of IV, intramuscular or intranasal NAD+ for cognition has been located; the trials in that space all used an oral precursor instead. The one placebo-controlled fatigue trial retrieved used oral NADH, a different molecule taken by a different route, in 86 adults over two months, and found no significant improvement on fatigue intensity, function or quality of life, its primary outcomes; only a small reduction in anxiety score and post-exercise heart rate reached significance (Alegre 2010). No interventional trial of direct NAD+ and exercise capacity was located, and the one relevant intranasal-NAD+ study tested olfactory recovery in mice, with the human component confined to cultured cells in vitro.
Safety
Two safety findings are documented rather than anecdotal, and point in different directions. The first is the infusion-tolerability pattern above: IV NAD+ was associated with moderate to severe gastrointestinal symptoms, increased heart rate and chest pressure during administration, in a controlled comparison against IV nicotinamide riboside, requiring roughly two and a half times the infusion time to keep symptoms manageable (Reyna 2026); standard hepatic, renal and inflammatory labs did not move significantly over 30 days in that dataset. The second is a documented manufacturing failure, not a property of the molecule. An FDA warning letter to a compounding outsourcing facility, dated 20 January 2026, names NAD+ specifically, reporting a lot found to contain excessive bacterial endotoxin, measured at 3,360 EU/mL, after which three patients experienced hypotension and fever, and a voluntary recall covering 56 sterile-product lots, with the endotoxin-contaminated NAD+ lot elevated to Class I, the classification reserved for a reasonable probability of serious harm or death. This is evidence that at least one compounder’s sterile-manufacturing process failed, not that NAD+ itself is inherently dangerous when properly compounded, and the two should not be collapsed together. No published protocol for cardiac pre-screening, infusion-rate titration or post-infusion monitoring was located, because there is no approved label to set one; no long-term controlled safety data for repeated IV NAD+ administration exists, and the longest controlled human exposure documented is seven days of dosing plus 30-day follow-up.
Regulatory status
NAD+ is not an FDA-approved drug for any indication, by any route. There is no NDA, ANDA or BLA covering it, no FDA label, no approved dose and no FDA-reviewed efficacy or safety data as a drug product. Everything sold clinically as IV NAD+ therapy, NAD+ injections or NAD+ nasal spray is compounded from bulk powder, not dispensed under an approved application, and compounded drugs are by definition not FDA-reviewed for safety or effectiveness. NAD+’s status on the FDA list of substances eligible for compounding from bulk remains unresolved years after nomination, and the warning letter above treats a compounder’s use of NAD+ as making an unapproved new drug. NAD+ does not appear on the current World Anti-Doping Agency Prohibited List, unlike the growth-hormone-releasing peptides discussed elsewhere on this site; as an endogenous metabolite present in every human cell, it sits in a different regulatory category, a factual contrast, not an endorsement of unsupervised IV use.
What circulates
Clinic-administered IV NAD+ is commonly marketed in per-session amounts described as roughly 250 mg to 1,000 mg, often front-loaded as a multi-day protocol and followed by periodic maintenance infusions. The one controlled dataset above used 500 mg per day for four days, the single figure in this range with a named, published source; the rest is a general market pattern, not sourced to any named vendor or dated. At-home injection kits are marketed at smaller amounts, tens to a couple hundred milligrams, often alongside precursor products rather than NAD+ alone. Nasal sprays are marketed at low-milligram per-spray amounts; no human clinical data on intranasal NAD+ absorption or effect in a wellness context has been located, and the only intranasal-NAD+ study found was the mouse and cell-culture olfactory-repair study above, not the kind of use these products market.
Measured against what has actually been studied, this range sits well above its own only controlled-source figure (500 mg over four days), and the marketed loading and maintenance schedule has no published trial testing that pattern for any outcome. The heart-failure trial’s 10 mg-per-day, seven-day protocol, the only randomized human dose with a positive result, is far below what wellness clinics typically infuse, and was tested under medical supervision in a cardiac population, not a wellness-seeking one. NAD+ is also frequently sold combined with glutathione, vitamins and amino acids, or with low-dose naltrexone or metformin in some registered trial designs, meaning a clinic’s reported patient experience is often the effect of a multi-ingredient protocol rather than NAD+ alone, mirroring the addiction pilot above. Marketing material typically cites general biochemical roles such as cellular energy or DNA repair without citing the thin human trial evidence in this entry, and without disclosing that the product is an unapproved compounded drug or that a documented tolerability profile and a 2026 endotoxin-related recall exist for this category.
What the record gets wrong
The central problem with IV and intranasal NAD+ is not that it has been shown not to work; it is that the basic premise behind giving it this way has not been shown to hold. Whether NAD+ delivered into the bloodstream or nasal passage raises NAD+ inside the cells it is meant to reach, rather than being broken down outside the cell with only smaller components taken back up, is open and contested, and no human study located here directly answered it by measuring intracellular NAD+ before and after infusion. Every downstream claim about cellular energy, DNA repair or anti-aging effect depends on that unresolved step.
Layered on that gap, the two claims driving the most consumer interest, anti-aging or wellness and addiction or withdrawal treatment, are the two with the least direct evidence: a 2026 systematic review found no eligible outcomes trial of IV or intramuscular NAD+ for either use, and the addiction claim rests on one uncontrolled 50-person pilot and unpublished conference material, not a randomized controlled trial. The one real randomized, placebo-controlled trial of direct NAD+ in humans found a modest ejection-fraction benefit in a cardiac population, at a fraction of the dose typically infused at wellness clinics, and its own authors call it preliminary. A separate, published comparison confirms IV NAD+ causes significantly more gastrointestinal and cardiac-adjacent symptoms than an IV precursor and takes substantially longer to infuse. And the FDA has documented an NAD+ lot contaminated with bacterial endotoxin severe enough to cause patient harm and trigger a Class I recall, inside a compounding supply chain with no FDA-approved manufacturing standard, because no FDA-approved NAD+ product exists.