NAD+ injections are sold for energy, focus and healthy aging. The benefits in the marketing are rarely tied to a study, so this article asks a narrower question. What have researchers measured when people were given NAD+ itself?
The short answer: two small intravenous studies, and nothing on injections under the skin or nasal sprays. The NAD+ guide sets out its regulatory status. This page covers the evidence behind the longevity claims.
What NAD+ is
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme in every cell. It carries electrons in the reactions that turn food into usable energy.
NAD is in FDA’s 503A Category 1. That list covers substances pharmacies may compound while the agency evaluates them. It makes compounded NAD+ legal to prescribe. It is not a finding that NAD+ works for anything.
What an infusion did to blood levels
The first question is whether NAD+ given from outside reaches the blood as NAD+. A pilot study infused NAD+ into healthy men aged 30 to 55 for six hours (n = 8), with a saline group for comparison (n = 3) [1].
Plasma NAD+ did not change for the first two hours. The authors concluded that NAD+ was rapidly and completely removed from the plasma over that period. NAD+ and a breakdown product then rose in the urine by six hours [1].
The study measured blood and urine chemistry only. It did not measure energy, mood, cognition or any marker of aging.
How people tolerated it
The second study is a review of records from one wellness clinic. It compared 6 clients given 500 mg of intravenous NAD+ with 8 given nicotinamide riboside, on four days in a row [2].
Clients on NAD+ reported moderate to severe stomach symptoms, a faster heart rate and chest pressure during the infusions. Their infusions ran 97 minutes on average against 37, because the drip was slowed. HDL cholesterol fell in the NAD+ group [2].
This was not a trial. Nobody was randomized, and every author worked for the clinic that sells the infusions.
Injections under the skin and nasal sprays
Most telehealth sellers prescribe NAD+ as an injection under the skin, and some as a nasal spray. No published study has measured either route in people. The only nasal NAD+ efficacy study found was in mice with chemically induced loss of smell [3].
Why pill studies do not answer the question
Oral precursors such as nicotinamide riboside are different molecules. The body converts them into NAD+. In 30 healthy middle-aged and older adults, nicotinamide riboside was well tolerated and stimulated NAD+ metabolism [4].
In 40 men with obesity, 2,000 mg a day for 12 weeks did not improve insulin sensitivity, energy expenditure or body composition [5]. Neither result tells you what an NAD+ injection does.
What this means for NAD+ injection benefits
Every benefit claimed for NAD+ injections is, for now, not studied in people. That does not show the injections fail. It shows nobody has run the trial.
If a seller cites a study for NAD+ injections, check whether it tested NAD+ itself, by that route, in people. The reviews of Breeze Meds and CoreAge Rx set out what each claims for its NAD+ and what it cites.