NAD+ Dosage: The Doses Studied, Not the Doses Prescribed

Before the details

This is a research digest, not dosing guidance, and it gives no instructions for taking anything. Below are the doses that appeared in published studies — the amount a trial gave its participants, with the route (by mouth, or by IV drip) and how long it ran. "Half-life" here means how long the substance lingers before the body clears it. Read these as a record of what researchers tested, not as a plan for you.

Doses Used in NAD+ and Precursor Research

NAD+ dosage in the literature is almost always precursor dosage, by mouth, plus a smaller set of IV NAD+ protocols. The figures below are study doses, reported here for reference only.

• NMN (oral precursor): 250-900 mg/day in human randomized trials; 250 mg/day is the most-replicated dose ^[1], and the 300/600/900 mg/day multicenter trial identified 600 mg/day as optimal for raising blood NAD+ ^[3].
• NR (oral precursor): 250-1000 mg/day commonly, with 100/300/1000 mg/day producing 22%/51%/142% whole-blood-NAD+ rises ^[4]; up to 3000 mg/day has been tested for safety.
• IV NAD+ (wellness/clinical): reported infusion protocols of roughly 250-1000 mg per session over several hours; a pharmacokinetic study used 750 mg over 6 hours ^[6], and a cognition pilot used 750 mg/day for 5 consecutive days ^[9].
• Nicotinamide (NAM): studied at 500 mg twice daily in other contexts; topical formulations are used for skin ^[12].

None of these is a recommendation. They are the numbers the cited trials used.

How Long Does NAD+ Last? (Clearance and Persistence)

NAD+ half-life depends entirely on the route, and the two routes behave nothing alike. Infused IV NAD+ is rapidly cleared from plasma: the 6-hour pilot found plasma NAD+ undetectable for roughly the first 2 hours of infusion, with extensive extracellular metabolism shunting it toward methylated nicotinamide metabolites measured in urine ^[6]. So an IV "dose" does not sit in the blood as NAD+; it is processed quickly. Oral precursors behave oppositely on the measurable readout: they are absorbed and raise whole-blood NAD+ over days, with the elevation persisting through chronic dosing across 8-to-12-week trials ^[3][4]. The persistence is in the NAD+ pool the precursor builds, not in the molecule that was swallowed.

Tolerability and Adverse Events in NAD+ Studies

NAD+ side effects track the route. Oral precursors are generally well tolerated. NR at 100-1000 mg/day for 8 weeks showed no significant adverse-event difference from placebo and no flushing ^[4]; the NMN multicenter trial reported no safety issues at 300-900 mg/day over 60 days ^[3]; the 250 mg/day NMN trial reported no change in body composition ^[1]. IV NAD+ is where the adverse events concentrate. If infused too fast, IV NAD+ can cause chest/abdominal discomfort, flushing, and nausea; the 750 mg pilot recorded chest tightness and abdominal discomfort at higher infusion rates ^[6]. A real-world retrospective comparison found IV NAD+ (500 mg) associated with moderate-to-severe gastrointestinal symptoms, elevated heart rate, and chest pressure, requiring mean infusion times of 97 minutes, whereas IV NR (500 mg) caused only mild tingling and took about 37 minutes ^[15].

Two documented quality risks belong on the record. Compounded injectable NAD+ carries contamination risk: the FDA has issued a Class I recall of a compounded NAD+ injection for elevated bacterial endotoxin. And a theoretical caution exists that boosting NAD+ could support the metabolism of existing cancers, since NAD+ fuels proliferating cells — its role in oncology is context-dependent ^[14].

Routes studied and stability notes

Oral (NMN, NR, nicotinamide capsules and powder) carries the bulk of controlled human evidence. IV NAD+ infusion is used in wellness clinics with limited, mostly pilot or retrospective data ^[6][9][15]. Subcutaneous and intramuscular NAD+ injection are compounded with minimal peer-reviewed pharmacokinetic data. Sublingual, intranasal, topical, and transdermal-patch products are marketed with little controlled evidence. On stability: NAD+ and NMN are hygroscopic and degrade with heat and moisture; reconstituted injectable NAD+ should be kept cold and protected from light, and compounded injectables carry the endotoxin/contamination risk noted above ^[14].

How much NAD should I take?

This is a research digest, not dosing guidance. The cited human trials used NMN at 250-900 mg/day ^[1][3], NR at 250-1000 mg/day with up to 3000 mg/day tested for safety ^[4], and reported IV protocols of roughly 250-1000 mg per session ^[6][9]. Those are study doses, described as research, not a recommendation for any person.

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

The cited trials did not establish an optimal time of day. NAMPT, the rate-limiting salvage enzyme, follows a circadian rhythm and is induced by exercise ^[5], but the literature summarized here provides no timing recommendation. Any time-of-day claim is outside what these studies measured.