NAD+ doses used in research, walked route by route

The short version

This page reports the NAD+ doses studied — and gives no instructions to take anything. In plain terms: when researchers tested NAD+, they almost always tested a precursor (the building blocks NMN or NR) by mouth, because intact NAD+ absorbs poorly. Oral NMN trials ran roughly 250–900 mg per day; oral NR trials ran roughly 250–3000 mg per day. IV infusions in wellness settings report around 250–1000 mg per session. Below, each route is laid out with what the studies used and a clear note on its limits. None of this is dosing advice; it is a map of what has been administered in published research.

NAD+ and Precursor Doses Used in Research

Any discussion of NAD+ dosage has to start with the precursor caveat, because intact NAD+ is rarely what gets dosed. Oral precursors dominate the controlled human evidence, and the ranges are well defined. NMN has been studied at 250–900 mg/day in human RCTs, with 250 mg/day the most-replicated dose and up to about 1200 mg/day reported ^[1][3]. The lowest of those — 250 mg/day for 10 weeks — was enough to improve muscle insulin sensitivity in prediabetic women, which suggests the effective window does not necessarily sit at the top of the range ^[1]. The multicenter NMN trial compared 300, 600, and 900 mg/day directly and flagged 600 mg/day as optimal for raising blood NAD+, with no added benefit and no safety penalty at 900 mg/day ^[3].

Nicotinamide riboside has been studied across a wider band: commonly 250–1000 mg/day, with up to 3000 mg/day tested for safety in Parkinson's-disease research ^[4]. The NR dose-response trial used 100, 300, and 1000 mg/day and saw whole-blood NAD+ rise 22%, 51%, and 142% respectively — a clean monotonic relationship where more dose meant more blood NAD+ across the tested range ^[4]. The vitamin-B3 form nicotinamide has been studied at 500 mg twice daily in skin-cancer chemoprevention work ^[12]. These figures describe what was administered in studies; they are not a recommendation to take any amount, and the existence of a studied dose says nothing about whether any individual should use it.

Routes studied: oral, IV, injection, and the rest

Four route families appear in the literature, with very different evidence behind them. Oral capsules and powders of NMN, NR, and nicotinamide carry the bulk of the controlled human evidence, and they are where the dose-response data above come from ^[4][3]. Intravenous NAD+ infusion is used in wellness clinics with limited, mostly pilot and retrospective data; reported protocols run roughly 250–1000 mg per session over several hours, and one pharmacokinetic study used a 3 µmol/min continuous infusion over six hours ^[15]. Subcutaneous and intramuscular NAD+ injection is compounded with minimal peer-reviewed pharmacokinetic data, and sublingual, intranasal, topical, and transdermal-patch products are marketed with little controlled evidence ^[15].

The practical takeaway is that evidence quality drops sharply as you move from oral precursors to IV to patches. The oral-precursor route has multiple randomized, placebo-controlled trials behind it; the IV route has small pilot and retrospective reports; the patch and sublingual routes have largely marketing claims. Route matters for more than convenience — it determines whether there is any controlled human data at all. Where a route lacks that data, this site says so rather than filling the gap.

Half-life, absorption, and what reaches the blood

NAD+ itself is not freely taken up intact by most cells, and infused IV NAD+ is rapidly cleared from plasma — a pilot study found near-complete plasma removal within roughly the first two hours of infusion ^[15]. That rapid clearance is one reason the IV route's durability is questioned: the molecule that goes in does not linger in the blood the way a sustained drug level would.

Oral precursors behave differently. They are absorbed, routed through the salvage and NRK pathways, and raise whole-blood NAD+ over days to weeks, with the elevation sustained through chronic dosing across 8–12-week trials ^[4][3]. This is why precursor trials measure whole-blood NAD+ as their pharmacodynamic readout rather than a classic plasma half-life — the meaningful signal is the standing rise in the NAD+ pool, not the transit time of any single molecule.

Stability is a practical footnote. NAD+ and NMN are hygroscopic and degrade with heat and moisture, so reconstituted injectable NAD+ should be kept cold and protected from light [as documented in the stability record]. And compounded injectables carry contamination risk — an FDA Class I recall has been issued for a compounded NAD+ injection over elevated endotoxin, a documented quality failure rather than a property of the molecule itself.

How much NAD should I take?

This is a research digest and gives no dosing instructions. For context only, studies have used oral NMN at 250–900 mg/day and oral NR at 250–3000 mg/day, while IV NAD+ protocols report roughly 250–1000 mg per session ^[3][4][15]. Doses studied are not a recommendation, and this site does not advise any amount.

What is the best time to take NAD, morning or night?

No trial establishes an optimal time of day. NAD+ synthesis follows a circadian rhythm via the NAMPT salvage enzyme, but human studies have not compared morning versus evening dosing ^[5]. We report this rather than advise a schedule.