NAD+

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme every cell uses to move energy and keep its repair systems running. It shuttles electrons through the stages of energy production, and it is the fuel that three families of enzymes consume when they control DNA repair, gene activity, and stress responses ⁶.

Cells make NAD+ three ways: from the amino acid tryptophan in the diet, from nicotinic acid, and through a salvage route that recycles nicotinamide and accepts the precursors NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) ¹⁵. Baseline needs are small. Dietary tryptophan or under 20 mg of niacin per day covers them ²¹.

As a therapy, NAD+ itself is given intravenously, because oral NAD+ is degraded in the gut. Oral regimens use the precursors NMN and NR instead ¹. The first human trial of an oral precursor's effect on blood NAD+ appeared in 2017, roughly doubling whole-blood NAD+ within 9 days ¹³. A 2018 study of 1,000 mg IV NAD+ daily for 6 days in adults aged 70 to 80 brought IV NAD+ into the clinical literature ⁴. Commercial IV NAD+ clinics have since grown faster than the evidence, which is why systematic reviews stress that efficacy and long-term safety remain open questions ¹.

NAD+ has two jobs. First, it carries electrons through energy metabolism: in its oxidized form it accepts electrons from the breakdown of sugars and fats and passes them into the mitochondrial machinery that makes ATP ⁶. Second, it is a consumed substrate. Certain enzymes literally spend NAD+ when they run ⁶.

The spending family that matters most for longevity research is the sirtuins (SIRT1 through SIRT7), enzymes that strip chemical tags called acetyl groups off proteins to change their activity. Sirtuins couple NAD+ hydrolysis to deacetylation of proteins that control metabolism, epigenetic marks, and stress responses ⁶. SIRT1, SIRT3, and SIRT6 are protective across cardiovascular disease models ²⁶. Two other enzyme families drain the same pool: PARP1/2, which rush to DNA damage sites, and CD38, which is active under chronic inflammation. When either is busy, less NAD+ remains for sirtuins ⁶.

Aging-related depletion has a defined driver in blood vessels. The enzyme AEP cleaves NAMPT, the rate-limiting enzyme of the salvage pathway, setting off systemic NAD+ depletion and vascular aging in mice; NMN supplementation reversed part of that decline ¹⁷.

In humans, a 6-day course of 1,000 mg IV NAD+ per day raised the blood NAD+ metabolome, increased SIRT1 and FOXO1 expression in immune cells, and lowered markers of oxidative stress and inflammation ⁴.

Oral precursors take a roundabout route. Most oral NMN and NR is converted by gut bacteria to nicotinic acid, which raises NAD+ through the Preiss-Handler pathway; enterohepatic circulation then delivers it preferentially to the liver ¹⁰. Reduced forms of these precursors, NMNH and NRH, are more potent NAD+ boosters that also trigger broader transcriptomic, proteomic, and metabolomic changes in hepatocyte models (in vitro), but their safety and clinical profile remain poorly characterized. In a 14-day human RCT, NR and NMN raised circulating NAD+ to a similar degree, while intact precursor exposure in blood was transient ⁹.

There is also an extracellular layer. NAD+ is rapidly degraded by enzymes on brain synapses, a reaction NMN can inhibit, and specific high-affinity binding sites sit on synaptic membranes, suggesting roles beyond the intracellular fuel pool ²⁷.

The evidence has a clear shape: pharmacokinetic target engagement is reliable, while functional outcomes remain small and mixed ⁷.

Blood NAD+ rises with oral precursors. NR at 1,000 mg twice daily doubled whole-blood NAD+ within 9 days in an open-label pharmacokinetic study ¹³. NMN 250 mg per day for 6 to 12 weeks raised whole-blood NAD+ and its metabolites in healthy older men, with small improvements in gait speed and grip strength but no change in body composition ¹². A 14-day randomized comparison found that NR and NMN, but not nicotinamide, raised circulating NAD+ ⁹. In the brain, 1,200 mg per day of either precursor produced a measurable cerebral NAD+ increase by week 4 ¹⁴.

Intravenous effects. A 6-day course of 1,000 mg IV daily raised SIRT1 and FOXO1 expression, increased protective antioxidant enzymes, and lowered CRP, IL-6, and oxidative-stress markers in 8 adults aged 70 to 80 ⁴. A single rheumatoid arthritis case reported pain relief after four 250 mg infusions and ultrasound-confirmed resolution of joint inflammation (synovitis) at 9 months, though confounders prevent causal conclusions ⁵.

Fertility. In a retrospective cohort of 50 women under 35 with diminished ovarian reserve, NMN pretreatment alongside standard stimulation improved follicle growth (20.4 vs 15.7 mm), endometrial thickness (10.0 vs 7.7 mm), and pregnancy rate (48% vs 24%) ²³. This is observational, not a controlled trial.

Exercise caution. In a randomized crossover trial, NMN 1,200 mg per day for 7 days suppressed exercise-induced inflammation but abolished the normal 171% post-exercise rise in muscle mitochondrial content after blood flow restriction training ²².

Preclinical breadth. Animal work shows NMN benefits across kidney injury, heart-attack remodeling, and vascular aging, with mechanisms mapped to NAD+ synthesis enzymes ¹⁶. These studies establish mechanism rather than human efficacy.

Human data on intravenous NAD+ is limited to small studies: one pilot RCT, retrospective tolerability work, an open-label trial, and a case report. No outcomes trial has tested IV or IM NAD+ for anti-aging or wellness ⁷.

Published human IV protocols:

Protocol	Dose	Frequency	Duration	Evidence
Wellness clinic cohort	500 mg IV	Daily	4 days	Retrospective 2
Elderly healthy adults	1,000 mg IV	Daily	6 days	Open-label 4
RA case	250 mg in 500 mL saline over ~1 h	Every 2 weeks	4 infusions	Case report 5
Pilot RCT	500 mg IV	Single dose	1 infusion	RCT 3

Community and practitioner protocols run 250 to 1,000 mg per infusion over 1 to 4 hours, once to three times weekly, or as reset blocks of 4 to 10 consecutive daily infusions repeated a few times per year. Slower infusion reduces nausea and chest discomfort ². Published IV doses are fixed rather than weight-based, spanning roughly 2.5 to 18 mg/kg across the 250, 500, and 1,000 mg anchors ².

Oral precursor reference doses: NMN 250 mg per day for 6 to 12 weeks raises whole-blood NAD+ ¹²; NR up to 1,000 mg twice daily roughly doubled it within 9 days ¹³; 1,200 mg per day of either plateaus blood NAD+ in about 2 weeks ¹⁴. For consumers switching between precursors, approximately 1,150 mg NMN is molar-equivalent to 1,000 mg NR (systematic review). The highest published oral dose, microcrystalline β-NMN (MIB-626) at 1,000 mg twice daily, is under phase 2a investigation in diabetic kidney disease ¹⁹.

Timing: morning administration dominates practice (community protocol), and once-daily dosing is sufficient once levels plateau ¹⁴. For trainees, one crossover RCT suggests separating NMN from workouts when muscle adaptation to training is the goal, since a 7-day course blunted the post-exercise mitochondrial rise ²².

NAD+ for injection is supplied as a lyophilized (freeze-dried) powder or a compounded solution, and research protocols dilute it with 0.9% sodium chloride, also called normal saline, for intravenous infusion ². Reconstitute the powder with sterile water or saline, then buffer the acidic solution toward physiologic pH with sodium bicarbonate, titrating to roughly pH 5.5 to 6.5 for injection comfort (community protocol; practitioner consensus). The interactive calculator below works out the draw volume for a given vial size and dose.

Storage guidance differs before and after mixing. Lyophilized powder can be kept at room temperature per its label, protected from light and humidity. Once reconstituted, the solution belongs in a refrigerator at 2 to 8°C and should be used within the pharmacy-assigned beyond-use date, commonly 28 days under aseptic handling (community protocol; practitioner consensus). Avoid repeated freeze-thaw cycles, and discard any solution that is cloudy, discolored, or shows precipitate.

The molecule itself is fragile in solution. Enzymes called NADases clip the nicotinamide-glycoside linkage, splitting NAD+ into nicotinamide and ADP-ribose ²⁷, and accurate blood measurement requires rapid, standardized sample handling because NAD+ degrades so readily outside the body ⁸.

No formal human drug-interaction studies exist for NAD+ itself, so this section combines in-vitro, animal, and human evidence for NAD+ and its precursors NR and NMN.

Drugs

• Metformin: in diet-induced obese rats, NR plus metformin preserved hippocampal volume and spatial memory better than either agent alone ³⁹. Both compounds converge on NAD+/sirtuin and AMPK signaling ³⁷.
• NAMPT inhibitors (FK866 and related investigational AML agents): NR converts to NMN directly, bypassing the NAMPT block, and in primary AML samples NR rescued the cells from the anti-leukemic effect of NAMPT inhibition ³⁵. NAD+ precursors would antagonize this drug class.
• Taxanes and platinum chemotherapy: NR relieved paclitaxel-induced neuropathic pain in rats ⁴¹, but IV NR increased blood-vessel growth (angiogenesis) in a lung-carcinoma mouse model ⁴². Research reviews advise against co-use during active chemotherapy.
• Alcohol: consumption depletes NAD+ and blunts precursor efficacy, and IV NAD+ is used anecdotally in withdrawal protocols without controlled efficacy data ¹.

Supplements

• Niacin and nicotinamide: NR and NMN raise NAD+ largely through gut conversion to nicotinic acid via the Preiss-Handler pathway ⁹. In a 14-day RCT, NR and NMN, but not nicotinamide, raised blood NAD+ ⁹. Stacking multiple B3 forms adds toxicity risk without demonstrated benefit ²¹.
• Resveratrol: activates NMNAT1, the final NAD+ synthesis enzyme, raising intracellular NAD+ up to 5-fold in human astrocytes in vitro ⁴⁶. A common community stack with no human combination data.
• TMG (trimethylglycine): community protocols pair 500 to 1,000 mg TMG with high-dose precursors to buffer methylation demand from nicotinamide clearance.
• Exercise timing: in a crossover RCT, NMN 1,200 mg per day for 7 days suppressed exercise-induced muscle inflammation but abolished the normal post-exercise mitochondrial rise after blood-flow-restriction training ²². Research protocols separate NAD+ dosing from training.
• Urolithin A: shares the SIRT1/AMPK/PGC-1α mitophagy axis with NAD+ biology ⁴⁹. Combination unstudied.

Condition cautions

• Active malignancy: evidence is bidirectional. IV NR increased angiogenesis in a lung-carcinoma model ⁴², while NMN potentiated CAR-NK therapy in ovarian cancer ⁴³ and restored antitumor NK-cell function in DLBCL ⁴⁴. Reviews flag theoretical pro-tumor effects of sustained repletion ¹⁵.
• Unstable cardiovascular disease: IV NAD+ commonly causes gastrointestinal symptoms, faster heart rate, and chest pressure ².
• Gout: the nicotinic acid pathway can raise uric acid ²¹.
• Renal disease: NMN is nephroprotective in preclinical kidney-injury models ¹⁸, and a phase 2a diabetic kidney disease trial doses MIB-626 at 1,000 mg twice daily with safety results pending ¹⁹.
• Autoimmune disease: one RA case improved after IV NAD+ ⁵, NR suppressed psoriatic Th17 inflammation in mice ⁴⁵, and NAD+ IV triggered a white-cell rise in one pilot ³. Monitoring disease activity is the pattern in the literature.

Intravenous NAD+ in the literature is given as time-limited courses, not continuous therapy.

Regimen	Dose	Schedule	Evidence
Wellness clinic cohort	500 mg IV	4 consecutive days	Observational 2
Elderly pilot	1,000 mg IV	6 consecutive days	Open-label 4
Maintenance (RA case)	250 mg IV	Every 2 weeks, 4 infusions	Case report 5
Acute pilot dose	500 mg IV	Single infusion	RCT 3

No randomized trial has tested formal on/off schedules. Practitioner protocols commonly run 4 to 10 consecutive daily infusions of 250 to 1,000 mg, repeated every 4 to 12 weeks, with lower-dose maintenance between courses. Oral precursor cycling follows an 8 to 12 week on, 4 to 8 week off pattern in community practice.

Three rationales support intermittent use. First, the response is nonlinear and saturable: once blood NAD+ plateaus at about 2 weeks, more time on adds little ⁶. Second, most oral NR and NMN is converted by gut bacteria to nicotinic acid before it raises NAD+, so continuous dosing keeps a metabolic load on the microbiome ⁹. Third, tolerability: IV NAD+ commonly causes nausea, cramping, flushing, chest pressure, and faster heart rate, with 500 mg infusions averaging 97 minutes versus 37 for NR IV, plus a transient white-cell rise in one pilot ². Long-term continuous elevation has not been safety-tested, and reviews flag the theoretical pro-tumor potential of sustained repletion as one reason for intermittent use ¹⁵.

Signs a protocol break is warranted: intensifying infusion symptoms ²; fading subjective benefit; adverse lab shifts such as falling HDL-C or rising white-cell counts on repeat IV courses ²; being in an adaptation-focused training block, since NAD+ boosting can blunt exercise-induced mitochondrial adaptation ²²; or blood NAD+ already at plateau after 2-plus weeks of dosing ¹⁴.

NAD+ and its precursors appear in several rational combinations in the literature, though most lack controlled human data.

• Elamipretide (SS-31): the strongest direct evidence. NMN plus SS-31 co-therapy mitigated post-ischemic brain injury through TREM2 modulation in mice ⁴⁰, making this a mechanistically grounded mitochondrial stack.
• Resveratrol: synergizes by activating NMNAT1, the final NAD+ synthesis enzyme, raising intracellular NAD+ up to 5-fold in vitro ⁴⁶. Widely stacked in community practice; no human combination trials.
• BPC-157 and TB-500: no interaction data exist, but the mechanistic overlap on blood-vessel growth and tissue repair ⁴² is the rationale for recovery stacks. Research reviews advise avoiding such combinations in cancer contexts.
• GLP-1 receptor agonists (semaglutide, tirzepatide): no direct data, but both improve systemic metabolism. Community protocols monitor glucose when insulin or sulfonylureas are also used.
• Thymosin alpha-1 and other immune peptides: NAD+ restoration drives M1 macrophage polarization ⁴³ and restores NK-cell cytotoxicity ⁴⁴, so immune-potentiating stacks could be additive and untested. Research practice is to titrate one agent at a time.
• CD38 and PARP inhibitors (NAD+-sparing co-interventions): pharmacological inhibition of NAD+-catabolizing enzymes is under investigation to preserve NAD+ for sirtuins, but human co-therapy data are lacking ⁶. (mechanistic; review)
• Administration note: practitioner consensus is not to mix IV NAD+ with other peptides in a single infusion bag, since pH and osmolarity compatibility are uncharacterized.

In the United States, NAD+ has no FDA-approved drug indication for any condition. Intravenous NAD+ is delivered in wellness clinics through compounded sterile preparations, and the precursors NR and NMN are sold as dietary supplements; none of these are DEA-controlled substances ³². The National Institute on Aging geroscience framework lists NAD+ boosters as investigational, with human studies described as limited and mixed ³⁷. The furthest advanced regulatory-grade development is a registered phase 2a trial of microcrystalline β-NMN (MIB-626) for diabetic kidney disease, dosed 1,000 mg twice daily for 24 weeks (NCT05759468) ¹⁹.

No outcomes trial has evaluated IV or IM NAD+ for anti-aging or wellness, and systematic reviews judge the current evidence insufficient to support routine clinical or wellness use ⁷.

In the EU, NAD+ has no EMA marketing authorization. The main regulatory action concerns the precursor NMN: EFSA has assessed β-NMN under the Novel Foods Regulation as a food-use source, a legal prerequisite for marketing it in food supplements ³². In the UK, injectable NAD+ is an unlicensed medicine supplied as compounded or specials product, and NMN requires novel-food authorization. In Australia, NAD+ is not registered or listed on the ARTG for any therapeutic indication.

For sport, NAD+, NMN, and NR are not listed on the WADA Prohibited List in or out of competition. Athletes should verify current WADA guidance on intravenous infusion volumes before any clinic IV session.

Route determines the side-effect profile. Intravenous NAD+ produces infusion-related symptoms as its dominant adverse effect, while oral precursors are notably better tolerated ²⁹.

IV NAD+. Retrospective data on 500 mg daily for 4 consecutive days show moderate-to-severe gastrointestinal symptoms (nausea, cramping), increased heart rate, and chest pressure, with mean infusion times of 97 minutes versus 37 for NR IV. All symptoms resolved when the infusion stopped ². A pilot RCT found NAD+ IV produced more numerous and more severe infusion-related events than NR IV ³. A 6-day course of 1,000 mg per day in 8 adults aged 70 to 80 reported no major adverse events ⁴, and a single case at 250 mg every 2 weeks reported none ⁵.

Oral precursors. NR and NMN over weeks to months are generally well tolerated, with mild gastrointestinal upset, headache, and flushing the typical complaints ²⁹. NMN 250 mg per day for 12 weeks in older men showed no significant adverse effects ¹². One functional caution: NMN 1,200 mg per day for 7 days blunted the post-exercise rise in muscle mitochondria after blood-flow-restriction training ²².

Uncommon and theoretical. IV NAD+ raised white blood cells and neutrophils in one pilot, interpreted as a transient inflammatory response to the infusion ³. After a 4-day IV course, alkaline phosphatase fell within the normal range and HDL-C declined significantly ². In mice, high-dose intraperitoneal NMN reduced sperm count and vitality in a route-dependent manner, while oral NMN did not ³⁴. Cancer promotion remains theoretical: NAMPT inhibition, which depletes cellular NAD+, selectively kills AML stem cells ³⁵, and reviews flag potential pro-tumor effects of sustained elevation ¹⁵.

What the research does not cover. Long-term safety beyond weeks to months, human reproductive safety, systematic drug interactions, and the cardiac significance of infusion-related heart-rate rise in people with undiagnosed coronary disease ¹.

Contraindications in research practice. Known hypersensitivity; active malignancy (conservative avoidance outside oncology trials); hypotension or autonomic instability, given the heart-rate and chest-pressure effects of IV NAD+ ²; concurrent high-intensity training blocks ²²; pregnancy and breastfeeding; pediatrics. Monitoring in the literature includes baseline liver, kidney, lipid, and glucose panels plus CBC, vital signs during infusion, and follow-up labs at day 30, where white-cell, ALP, and HDL-C shifts were detectable ².

Whole-blood NAD+ can now be measured with standardized enzymatic cycling assays, which support tracking a personal baseline-referenced response rather than a population range ⁸. In a healthy population aged 18 to 70 years, these metabolites follow a normal distribution and remain unchanged during aging, and established disease-related or booster-treated reference values do not exist, so serial interpretation against the individual's own pre-treatment baseline is the working approach ⁸.