NAD+ dosage as studied in the literature, not as advice

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.