# NAD+ Dosage in the Research: Doses, Routes, and Clearance

> NAD+ dosage as studied: oral NMN 250-900 mg/day, NR 100-1000 mg/day, compounded IV NAD+ over hours. Research context only — no human dosing instruction. Cited.

The amounts and routes studied in published trials, reported for context only. This page gives no personal dosing instruction.

## Before the details

This page reports the NAD+ dosage figures that *appear in studies* — what researchers gave, to whom, by which route, for how long. It is a record, not a recommendation, and it contains no instruction on how much anyone should take. Two facts shape everything below. NAD+ itself is barely absorbed intact by mouth, so oral studies use precursors (NMN, NR — building blocks the body converts into NAD+). And the route changes the picture completely: oral precursors raise blood NAD+ over weeks, while infused IV NAD+ is cleared from the blood within hours [13].

## Doses used in the research

Across the controlled human literature, the studied amounts cluster by precursor and route. These are research-context figures only.

- **NMN (precursor), oral:** 250-900 mg/day in human randomized trials; 250 mg/day is the most-replicated dose, and doses up to 1200 mg/day have been studied [8][3]. The dose-ranging trial identified 600 mg/day as optimal on its endpoints [3].
- **Nicotinamide riboside (NR, precursor), oral:** 250-1000 mg/day commonly, with up to 3000 mg/day tested for safety (the NR-SAFE trial in Parkinson's disease). The 8-week dose-ranging study used 100, 300, and 1000 mg/day [4].
- **IV NAD+ (wellness/clinical):** reported infusion protocols of roughly 250-1000 mg per session delivered over several hours; one pharmacokinetic study used a continuous 3 µmol/min infusion over 6 hours.
- **Nicotinamide (NAM), oral:** 500 mg twice daily has been studied for skin-cancer chemoprevention.

The pattern that matters for safety is route, not just amount: oral precursors are absorbed and raise whole-blood NAD+ measurably and durably [4], whereas the IV route bypasses absorption entirely and behaves very differently in the body.

## Half-life and clearance in the research

NAD+ pharmacokinetics depend heavily on route. NAD+ itself is not freely taken up intact by most cells; infused IV NAD+ is rapidly cleared from plasma, with one pilot study finding near-complete plasma removal within roughly the first two hours of infusion [13]. Extracellular NAD+ is also processed *before* uptake: in human skin fibroblasts, surface ecto-enzymes degraded extracellular NAD to nicotinamide, NMN, and purine metabolites, with adenosine the principal product taken into cells and converted to ATP [13]. In other words, parenteral NAD+ is largely dismantled outside the cell.

Oral precursors behave the opposite way. They are absorbed and raise whole-blood NAD+ over days to weeks, and that elevation persists through chronic dosing — sustained across 8-to-12-week trials [4][3]. This sustained-versus-transient contrast is the core of the [IV NAD+ and injectable routes](/nad-safety) discussion.

## Routes studied

Four route classes appear in the literature, with very uneven evidence behind them:

- **Oral** (capsules or powder of NMN, NR, or nicotinamide) — the bulk of controlled human evidence [4][3][8].
- **Intravenous NAD+ infusion** (wellness clinics) — limited controlled data, mostly pilot or retrospective.
- **Subcutaneous / intramuscular NAD+ injection** (compounded) — minimal peer-reviewed pharmacokinetic data.
- **Sublingual, intranasal, topical, and transdermal patches** (marketed) — little controlled evidence.

A stability note worth flagging: NAD+ and NMN are hygroscopic and degrade with heat and moisture, and compounded injectables carry contamination risk — an FDA Class I recall has been issued for a compounded NAD+ injection over elevated bacterial endotoxin. The route with the most aggressive marketing has the least controlled evidence and the documented quality risk; the [doses used in studies](/dosage) that are best supported are oral-precursor doses.

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A safety-first reel of the NAD+ literature — what the trials cut to, where the evidence drops off, and nothing dispensed, prescribed, or sold.