REFERENCE / DOSE-BY-ROUTE · RESEARCH CONTEXT
NAD+ Dosage: What the Precursor Trials Administered, by Route
A research-context register of the doses, routes, and tolerability signals reported in the literature — documented as what trials administered, never as a recommendation to use any dose.
Before the numbers
This page lists doses that appear in published studies — and only that. Nothing here is a recommendation to take anything. Because oral NAD+ is poorly absorbed, the dose figures that matter are for the precursors (the building blocks the body converts to NAD+): NMN and NR. Each figure below carries its route, because an oral capsule dose and an IV infusion dose are not interchangeable. Where a number is human, it is tagged human; where it is from animals, it is tagged as such. Read these as documentation of what was studied.
Doses studied in the NAD+ precursor literature
The NAD+ dosage figures in the human record are precursor doses, oral, given as research context. NMN (oral): 250–900 mg/day in human RCTs, with up to 1200 mg/day studied; 250 mg/day is the most-replicated dose [1][3], and 600 mg/day was identified as the optimal dose in a 300/600/900 mg/day dose-finding RCT [3]. NR (oral): commonly 250–1000 mg/day, with up to 3000 mg/day tested for safety [4]. IV NAD+ (wellness/clinical): reported infusion protocols of roughly 250–1000 mg per session over several hours, and a formal pharmacokinetic study used a 3 µmol/min continuous infusion over six hours [10]. Nicotinamide (NAM): 500 mg twice daily has been studied in other contexts. Every one of these is a dose that was administered in a study — not a dose this digest endorses for anyone.
How long NAD+ persists: infused clearance vs precursor elevation
NAD+ has no single "half-life" number, because it behaves differently by route. NAD+ itself is not freely taken up intact by most cells; infused IV NAD+ is rapidly cleared, with a pilot study finding near-complete plasma removal within roughly the first two hours of infusion [10]. Oral precursors are different: they are absorbed and raise whole-blood NAD+ over days to weeks, with the elevation persisting through chronic dosing across 8–12 week trials [4][3]. So the relevant pharmacokinetic contrast is a short infusion spike versus a durable precursor-driven rise [10][4].
Tolerability and safety signals reported in trials
Across the oral-precursor trials, NAD+ side effects were generally minor. NR at 100–1000 mg/day for eight weeks produced no flushing and no significant adverse-event difference from placebo at any dose, and did not elevate LDL cholesterol [4]; NR up to 3000 mg/day has been tested for safety [4]. NMN at 300–900 mg/day for 60 days reported no safety issues at any dose [3], and a systematic review of ten NMN trials found only minor adverse events (8.2%, independent of NMN) with no serious events [15]. The exceptions are on the injectable side: IV infusions can cause flushing, nausea, and chest or abdominal discomfort if run too fast, and compounded injectables have carried contamination risk — the FDA issued a Class I recall of a compounded NAD+ injection for elevated endotoxin [11]. Supplement-grade product purity also varies, and third-party testing is not guaranteed.
Routes studied, and what each one tells you
Four route families appear in the literature, with very different evidence weights. Oral capsules and powders of NMN, NR, and nicotinamide carry the bulk of controlled human evidence [4][3][1]. Intravenous NAD+ infusion is used in wellness clinics with limited, mostly pilot or retrospective data [10]. Subcutaneous and intramuscular compounded NAD+ injection has minimal peer-reviewed pharmacokinetic data [11]. Sublingual, intranasal, topical, and transdermal patch forms are marketed but have little controlled evidence. The route is part of the dose: a figure is only interpretable alongside the way it was given. See the tolerability and safety signals above for how each route's risk profile differs.
Stability and product quality in the literature
Two practical points recur in the source material. First, stability: NAD+ and NMN are hygroscopic (they pull in moisture from the air) and degrade with heat and humidity, so reconstituted injectable NAD+ is described as needing cold storage and protection from light [8][11]. Second, product consistency: supplement-grade NMN and NR products vary widely in purity and actual content, and third-party testing is not guaranteed, which is one reason published trials — where the material is characterized — are a cleaner read of what a dose does than a shelf product is [8]. Neither point is a dosing instruction; both are documented context for interpreting the dose figures above.
The dose-finding signal is worth restating because it is the closest the literature comes to a defined oral target: in the multicenter NMN RCT, 300, 600, and 900 mg/day all raised blood NAD+ versus placebo, but 600 mg/day was identified as the optimal dose on the trial's combined endpoints [3]. That is a study conclusion about a study population, not advice for a reader.
How much NAD should I take?
This digest gives no personal dosing advice. For research context only: studied doses span NMN 250–1200 mg/day and NR 250–3000 mg/day orally; 250 mg/day NMN is the most-replicated dose [1] and 600 mg/day was identified as optimal in one dose-finding RCT [3]. Those are descriptions of what trials administered, not a recommendation for any individual.