# NAD+ Dosage in the Research Literature: Doses Studied, Routes, Half-Life > NAD+ dosage as studied, not prescribed: NMN 250-900 mg/day and NR 250-3000 mg/day in human trials, IV infusion protocols, half-life, and reported tolerability. Research figures, no instructions. The precursor and IV doses that appear in the cited literature, with routes tagged and half-life noted. Informational only. ## Before the numbers This page reports NAD+ dosage figures the way the studies reported them — what was given, to whom, for how long, and by which route. It is not a recommendation and contains no instruction to take anything. Two reminders carry the whole page. First, oral NAD+ itself is poorly absorbed; the figures below are mostly for precursors (NMN and NR), the building blocks the body turns into NAD+. Second, a dose that worked in a trial is a research observation in that population, not a dose for any individual. Numbers are tagged by route so an oral-precursor figure is never confused with an IV one. ## Doses studied in the research literature In human trials, NMN (a precursor) was studied at `250-900 mg/day` orally, with `250 mg/day` the most-replicated dose and up to `1200 mg/day` examined; the multicenter dose-ranging trial spanned `300/600/900 mg/day` and identified `600 mg/day` as optimal for raising blood NAD+ [3]. The insulin-sensitivity trial used `250 mg/day` for 10 weeks [11]. Nicotinamide riboside (NR, a precursor) was commonly studied at `250-1000 mg/day`, with the 8-week dose-ranging trial at `100/300/1000 mg/day` [4] and up to `3000 mg/day` tested for safety in a Parkinson's-disease study (NR-SAFE). Plain nicotinamide has been studied at `500 mg twice daily` for skin-cancer chemoprevention. For the injectable route, reported IV NAD+ protocols run roughly `250-1000 mg` per session over several hours, and one pharmacokinetic study used a continuous `3 umol/min` infusion over 6 hours [14]. These are doses observed in studies, presented as research figures only — not human dosing guidance. ### How much NAD should I take? This page reports doses studied in the literature — for example NMN `250-900 mg/day` and NR `250-1000` and up to `3000 mg/day` — rather than a recommendation [3][4]. It is informational only and is not human dosing guidance; whether, how, and how much to use is a decision for a qualified clinician, not this digest. ## Why most oral products are precursors NAD+ itself is a large, charged dinucleotide and is not freely taken up intact by most cells, so plain oral 'NAD+' is an inefficient way to raise the coenzyme. The body builds NAD+ through pathways that start from smaller molecules, and that is exactly where precursors enter. A precursor is a building block the body converts into NAD+ — NMN and NR are the common ones. NR is taken up and converted to NMN by NRK kinases, then to NAD+; NMN sits one step from NAD+ [5]. This is why nearly all of the strong oral human data come from NMN and NR rather than NAD+ capsules — they feed the salvage and NRK routes the cell already runs [4][7]. ## How long NAD+ and its precursors persist NAD+ half-life depends entirely on route. Infused IV NAD+ is cleared from plasma rapidly — a pilot pharmacokinetic study found near-complete plasma removal within roughly the first two hours, with the infused NAD+ extensively metabolized before plasma NAD+ rose [14]. Oral precursors behave oppositely: absorbed and converted over time, they raise whole-blood NAD+ over days to weeks, and the elevation persists through chronic dosing in 8-12 week trials [4]. After stopping an oral precursor, blood NAD+ returns toward baseline over weeks. There is no single 'NAD+ half-life' figure — the coenzyme is endogenous and continuously synthesized and consumed; what the trials track is the whole-blood NAD+ level as a pharmacodynamic readout, not the clearance of a drug. ## Routes studied Oral capsules and powders of NMN, NR and nicotinamide carry the bulk of the controlled human evidence [4]. Intravenous NAD+ infusion is used in wellness settings with limited, mostly pilot or retrospective data [14]. Subcutaneous and intramuscular NAD+ injection is compounded with minimal peer-reviewed pharmacokinetics. Sublingual, intranasal, topical and transdermal-patch NAD+ products are marketed but have little controlled evidence behind them. A stability note matters for the injectable routes: NAD+ and NMN are hygroscopic and degrade with heat and moisture, and reconstituted injectable NAD+ should be kept cold and protected from light. Compounded injectables also carry contamination risk — the FDA has issued a Class I recall of a compounded NAD+ injection over elevated endotoxin. ## Tolerability and adverse events reported in trials In the cited oral-precursor trials, NAD+ side effects were generally mild and similar to placebo. The 8-week NR dose-ranging trial reported no flushing and no significant adverse-event difference from placebo at `100/300/1000 mg/day`, and NR did not elevate LDL cholesterol [4]. The NMN trials at `300/600/900 mg/day` and `250 mg/day` reported good tolerability and no serious adverse events [3][11]. The clearest documented risks attach to the injectable and IV routes: the FDA Class I endotoxin recall of a compounded injectable NAD+, and transient infusion-related chest pressure, abdominal discomfort, flushing and nausea when an IV is run too fast, which resolve on completion of the infusion. A separate theoretical concern — that boosting NAD+ could support the metabolism of existing cancers — has prompted caution in cancer populations, because NAD+'s role in oncology is dual and context-dependent. This describes what studies and reports observed; it is not safety advice. --- A signal-clean readout of the NAD+ literature — the precursor trials that actually moved whole-blood NAD+ logged in their own oral channel, plain oral NAD+ and the weak-evidence IV route kept on separate channels, and the unsettled NMN status reported as filed; no clinic behind this console and nothing here dosed, dispensed, or sold.