Three routes, three different numbers
An IV figure is a per-session total delivered over hours. An injection figure is milligrams per subcutaneous dose, which on the syringe becomes a count of units that depends entirely on the vial’s concentration. An oral figure is milligrams per day of a precursor, NR or NMN, which is not NAD+ and is not converted to it one for one. Every dosage argument on a forum that mixes two of these is comparing different quantities. Keep the route in front of the number.
What the oral NR trials used
Five controlled studies carry the human dosing data for NR.
A 2017 open-label pharmacokinetic study in eight healthy volunteers started at 250 mg, stepped up to 1,000 mg twice daily by days 7 and 8, and measured a 24-hour profile after a 1,000 mg dose. Steady-state blood NAD+ rose by 100% over baseline, the rise tracked blood NR closely, and there were no adverse events.
An eight-week randomized, double-blind, placebo-controlled trial in healthy overweight adults compared 100, 300 and 1,000 mg of NR per day. Whole-blood NAD+ rose dose-dependently, by 22%, 51% and 142%, within two weeks and held there for the rest of the study. There was no flushing and no difference in adverse events between NR and placebo or between doses, and NR did not raise LDL cholesterol. The manufacturer funded the study and two authors are its employees.
A two-by-six-week randomized, double-blind, placebo-controlled crossover trial in healthy middle-aged and older adults found chronic NR well tolerated and effective at stimulating NAD+ metabolism, with a signal toward lower blood pressure and arterial stiffness that the authors flagged for future trials rather than claimed.
A twelve-week randomized, placebo-controlled trial in forty obese, insulin-resistant men aged 40 to 70 used 1,000 mg twice daily, 2,000 mg per day. It was safe on blood tests and adverse events, and it improved nothing it set out to improve: not insulin sensitivity, glucose production or disposal, resting energy expenditure, lipolysis, or body composition.
A 21-day randomized, double-blind, placebo-controlled crossover trial in twelve aged men used 1 g per day. NR reached skeletal muscle and raised its NAD+ metabolome, lowered circulating inflammatory cytokines, and did not change mitochondrial bioenergetics.
Read together: the highest dose raised the biomarker the most, and the largest and longest trial at the highest dose measured no metabolic benefit. A dose that moves blood NAD+ is not the same as a dose that does something you can measure in the body.
What the NMN trial used
A 2023 randomized, multicenter, double-blind, placebo-controlled trial gave 80 healthy middle-aged adults placebo, 300, 600 or 900 mg of NMN once daily for 60 days. Blood NAD rose in every NMN group at day 30 and day 60, and was highest at 600 and 900 mg. Six-minute walking distance improved over placebo in all three NMN groups at both time points, with the longest distances at 600 and 900 mg. Blood biological age, by an algorithmic estimate, rose in the placebo group and held steady on NMN. Insulin resistance by HOMA-IR did not differ from placebo. No safety issues were found. The first author is employed by an NMN company, which is the usual pattern in this literature.
What the one NAD+ infusion study measured
The only published human data on NAD+ itself entering the body is a 2019 pilot that infused NAD+ intravenously at 3 micromoles per minute for six hours, which works out to about 700 mg in total. Plasma NAD+ and its metabolites did not change at all until after two hours; NAD+ and methylnicotinamide then appeared in urine at six hours. The authors’ reading was that, at that rate, NAD+ is rapidly and completely removed from the plasma for at least the first two hours. It was being taken up or broken down as fast as it was delivered. The study measured the metabolome. It did not measure energy, mood, cognition or anything else a patient would notice, and it did not compare doses. The chest pressure, nausea and cramping that make infusion clinics slow the drip are practice reports, not trial data; the pilot’s abstract carries no tolerability results.
Subcutaneous NAD+: what is and is not known
There is no dose-finding trial for subcutaneous NAD+. The schedules in circulation are clinic protocols. What a prescriber sets is the milligrams per injection, the frequency, and whether to step up. PepScribe’s NAD+ page describes what its clinicians prescribe as a small subcutaneous injection on a daily or every-other-day schedule, or a daily metered nasal spray, with the choice made in the free online visit. A protocol copied from a forum omits the two things that make it usable: the concentration of the vial it was written for and the history of the person it was written for.
The NAD+ dosage calculator: the arithmetic
Every “NAD+ dosage calculator” does one conversion. Milliliters equal the prescribed milligrams divided by the vial’s concentration in milligrams per milliliter, and units on a U-100 insulin syringe equal milliliters times 100. A 50 mg dose drawn from a vial labelled 200 mg/mL is 0.25 mL, which is 25 units. The same 50 mg from a 100 mg/mL vial is 0.5 mL, which is 50 units. That is why the same milligram dose reads as different unit counts from one pharmacy to another, and why a units figure without its concentration is meaningless. The concentration is on the label; the dose is on the prescription; if the two do not resolve to a clean number of units, the pharmacy or clinician answers the question, not a forum.
Why compounded NAD+ has no label dose
Injectable NAD+ is prepared by compounding pharmacies under an individual prescription. It is not an FDA-approved drug, so it has no approved dose, no approved indication and no approved labelling; the dose is a clinical decision made for one patient, which is the whole reason the prescription exists. NR and NMN are sold as dietary supplements, which is why the controlled dosing data exist for them and not for the injection.
How to get NAD+ prescribed online
At PepScribe the online visit is free. A US-licensed clinician reviews your history, and if NAD+ is appropriate, sets the form, the dose and the schedule. If prescribed, every dose is compounded in the USA by a licensed 503A pharmacy and shipped to you with supplies and dosing instructions, from $99/mo with medication, clinician care and shipping included. Compounded NAD+ is not FDA-approved. The NAD+ injections guide covers what NAD+ is and what the trials measured, the NAD+ injection cost guide covers the market, and the how to get NAD+ online guide walks through the telehealth path.
Frequently asked questions
What is the standard NAD+ injection dose?
There is none established by a trial. The dose, frequency and any step-up are set by the prescribing clinician. PepScribe's page describes a daily or every-other-day subcutaneous injection, or a daily nasal spray, decided in the free online visit.
How many units of NAD+ should I inject?
Units depend on the vial's concentration, so no one can answer without the label. Milliliters equal milligrams prescribed divided by mg/mL on the vial; units on a U-100 syringe equal milliliters times 100. A 50 mg dose is 25 units from a 200 mg/mL vial and 50 units from a 100 mg/mL vial.
What NAD+ dosage did the clinical trials use?
For oral NR: 100 to 1,000 mg per day in the dose-ranging trial, 1 g per day for three weeks in aged men, and 2,000 mg per day for twelve weeks in obese men. For NMN: 300, 600 and 900 mg per day for 60 days. For NAD+ itself: a single six-hour infusion of about 700 mg in one pilot study. No trial has tested subcutaneous NAD+ doses.
Is a higher NAD+ dose better?
Higher NR doses raised blood NAD+ more, and 2,000 mg per day for twelve weeks measured no metabolic benefit. In the NMN trial, blood NAD was highest at 600 and 900 mg, and walking distance improved in all three dose groups. More raised the biomarker more; it did not buy a measured result.
Can you take too much NAD+?
Oral NR up to 2,000 mg per day for twelve weeks produced no serious adverse events in trials, and the dose-ranging trial found no difference in side effects between doses. Long-term safety of sustained high-dose NAD+ repletion in humans has not been established. With infusions, symptoms during a session track the infusion rate, which is why clinics run them over hours.
Is NAD+ FDA-approved?
Compounded injectable and nasal NAD+ are not FDA-approved. NR is a dietary ingredient the FDA has accepted as generally recognized as safe for use in foods; NMN is sold as a supplement. None of these is an approved drug with a labelled dose.
