NAD+ dosage as it appears in the research record — doses, routes, and clearance.

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 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 that are best supported are oral-precursor doses.