# NAD+ Dosage in the Research: Precursor Doses, IV Protocols, Half-Life > NAD+ dosage as studied, not advised: NMN ~250-900 mg/day, NR ~250-1000 mg/day, IV 750 mg/day, plus half-life and tolerability. Research framing only — no dosing instructions. The precursor and IV doses that appear in human trials, what they measured, how NAD+ clears, and what was tolerated — research context only. ## The short read This is a research digest, and it gives no dosing advice for any person. It records the NAD+ dosage figures that appear in published studies so a reader can see what was tested. Because intact NAD+ is barely absorbed by mouth, the oral doses below are precursors (building blocks the body converts into NAD+) — NMN and NR — not NAD+ itself. The IV figures are clinic/research infusion protocols, not consumer instructions. Everything here is "studied at X" framing; nothing here is "take X." ## Doses used in the research (precursors and IV) Human trials cluster around a handful of figures. For NMN (a direct precursor one step from NAD+), studies used roughly 250-900 mg/day orally, with 250 mg/day the most-replicated dose and up to 1200 mg/day studied; the multicenter trial identified 600 mg/day as optimal for raising blood NAD+ [1][3][21]. For NR (the most clinically studied oral booster), studies used roughly 250-1000 mg/day, with up to 3000 mg/day tested for safety in a Parkinson's-disease trial [4][21]. Plain nicotinamide (NAM) has been studied at 500 mg twice daily for skin-cancer chemoprevention. For IV NAD+, reported wellness and clinical infusion protocols run roughly 250-1000 mg per session over several hours; the cited cognition pilot used 750 mg/day over 5 consecutive days, and a pharmacokinetic study used a continuous 3 µmol/min infusion over 6 hours [7]. These are infusion schedules from the literature, not timing or dosing guidance. ## Clearance and half-life of infused NAD+ NAD+ itself is not freely taken up intact by most cells, which is why route matters so much. Infused IV NAD+ is rapidly cleared from plasma — a pilot pharmacokinetic study found near-complete plasma removal within roughly the first two hours of infusion [7]. Oral precursors behave differently: they are absorbed and raise whole-blood NAD+ over days to weeks, with the elevation persisting through chronic dosing across 8-12 week trials [3][4]. So an IV bolus produces a brief plasma spike that clears within hours, while oral NMN or NR produces a sustained blood-NAD+ rise — a key reason the two routes are read on separate channels. ## Routes studied, stability, and quality risk Oral capsules and powders of NMN, NR, and nicotinamide carry the bulk of the controlled human evidence [3][4]. Intravenous NAD+ infusion is used in wellness clinics but rests on limited, mostly pilot or retrospective data [7]. Subcutaneous and intramuscular NAD+ injection is compounded with minimal peer-reviewed pharmacokinetic data, and sublingual, intranasal, topical, and transdermal-patch forms are marketed with little controlled evidence. Stability and quality are real variables. 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 carry contamination risk — the FDA has issued a Class I recall of a compounded NAD+ injection for elevated bacterial endotoxin. Supplement-grade purity and actual content vary widely, and third-party testing is not guaranteed. ## Tolerability and reported adverse events Oral precursors were well tolerated in the controlled trials. NR at 100-1000 mg/day for 8 weeks produced no flushing and no significant adverse-event difference from placebo at any dose, and did not elevate LDL cholesterol [4]. The multicenter NMN trial at 300-900 mg/day reported no safety issues at any dose over 60 days [3], and across reviewed precursor trials no moderate or severe adverse events were reported in the rare-disease studies [13]. The reported discomfort is concentrated on the IV route: infused NAD+ can cause chest or abdominal discomfort, flushing, and nausea if run too fast, symptoms that typically resolve on completing the infusion. None of this is individualized guidance — it summarizes what studies recorded. ## Two cautions that sit beside the dose figures Reading the dose figures honestly means reading two cautions alongside them. First, the headline result is pharmacodynamic, not clinical: raising blood NAD+ is well demonstrated, but a 2025 review concluded that translation to hard outcomes such as longevity or disease prevention in humans remains unproven, and that much of the strongest anti-aging data comes from rodents that may not extrapolate [21]. A dose that reliably moves a blood marker is not the same as a dose shown to change health. Second, a theoretical concern exists that boosting NAD+ could support the metabolism of existing cancers, because NAD+ supports proliferating cells; NAD+ in oncology has dual, context-dependent roles, which is why reviews advise caution in cancer populations [5][21]. Neither point is a dosing instruction; both are context a careful reader of the dose literature should carry. ## How much NAD should I take? This is a research digest and gives no dosing advice. For context only, human trials used NMN at roughly 250-900 mg/day and NR at roughly 250-1000 mg/day, with up to 3000 mg/day of NR tested for safety [3][4][21]. These are study doses, not a recommendation to take any product or amount. --- The NAD+ literature read like an order book — the coenzyme and its precursors NMN and NR each listed apart, the blood-NAD+ the trials actually moved quoted to source, and the rapidly-cleared IV route flagged as the weak-data listing; no clinic behind this desk and nothing here ordered, infused, dispensed, or sold.