NAD+ Injections Before and After: What Was Actually Measured

The "before and after" that NAD+ studies reliably show is a lab value: NAD+ and its breakdown products rise in the blood. The outcomes people buy NAD+ injections for, such as energy, focus, skin and slower aging, have not been tested in a controlled trial of injected or IV NAD+. A 2026 systematic review found no eligible outcomes trial of intravenous or intramuscular NAD+ for anti-aging or wellness at all¹.

What rises, and what doesn't

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme every cell uses to turn food into energy and to run repair enzymes. It declines with age, which is the whole case for topping it up¹.

The human evidence splits cleanly in two. The same 2026 review identified 33 human intervention studies of NAD-related compounds, 28 of them randomized. Oral precursors "consistently demonstrated biochemical target engagement," meaning blood NAD+ markers went up. Effects on function, metabolism, blood vessels and other healthspan outcomes were "heterogeneous and often null or endpoint-specific"¹.

That gap between a marker and an outcome is the recurring problem across peptide and supplement research. Our piece on surrogate endpoints explains why a rising number is not a result.

Injection and IV studies, tabled

These are the published human studies that put NAD+ itself into a vein.

The first study was designed to see where infused NAD+ goes. Over a six-hour infusion, plasma NAD+ and its metabolites did not change for at least two hours; the authors concluded it was being rapidly and completely removed from the blood. Breakdown products and NAD+ itself later appeared in urine². The study measured no effect on how anyone felt, because that was not its question.

The heart failure trial is the strongest evidence for injected NAD+, and it is about a disease, not wellness. At one month, left ventricular ejection fraction was 45.44% on NAD+ against 42.44% on placebo. The drop in NT-proBNP, fewer major cardiac events, and better symptom class all trended in NAD+'s favor without reaching statistical significance³. Our NAD+ page covers this trial in more detail.

The side effect clinic photos leave out

The third study is the only one that reports what commercial NAD+ infusions feel like. It is a retrospective chart review of clients at a commercial IV clinic chain, written by the chain's own employees, comparing four daily 500 mg infusions of NAD+ with the same of nicotinamide riboside (NR)⁴.

Every one of the six NAD+ clients reported moderate to severe symptoms during the infusion: abdominal cramping, diarrhea, nausea, vomiting, a faster heart rate and chest pressure. The symptoms stopped once each infusion ended. Because of them, NAD+ infusions took an average of 97 minutes against 37 minutes for NR. Liver, kidney, thyroid and inflammation markers did not change over 30 days⁴.

Six people is a tiny sample, and this study cannot tell you how common those reactions are. It does show that "before and after" for an NAD+ drip includes the during, and the during is often unpleasant. One contrast stands out: the 2019 pilot, which ran its infusion over six hours, recorded no adverse events².

Nasal spray: what has been studied

NAD+ nasal sprays are sold on the same claims as injections. The human evidence for them is thinner still.

A PubMed search in September 2026 for NAD+ together with intranasal or nasal spray, with human-study terms added, returned 11 records. None was a human study of NAD+ nasal spray. The one study that tested intranasal NAD+ directly was in mice with a chemically induced loss of smell, alongside experiments on cultured human olfactory stem cells. The mice recovered some sense of smell⁵. That is a lead for treating smell loss, not evidence about energy or aging in people.

A ClinicalTrials.gov search for "intranasal NAD" in the same month returned three records, for naloxone, fentanyl and insulin. None tested NAD+. A control search for semaglutide in the same pass returned 789 records, so the search itself was working.

NR and NMN: the trials that did the measuring

Most of the controlled human evidence behind NAD+ comes from oral precursors, nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), which the body converts into NAD+. They are different products taken a different way, but they show what happens when NAD+ is raised and outcomes are actually measured.

In the 2018 crossover trial, NR raised NAD+ in blood cells by about 60% compared with placebo. The physiological measures were exploratory, and the authors framed blood pressure and arterial stiffness as the most promising questions for larger trials, not as findings⁶. In obese, insulin-resistant men, 12 weeks of NR at 2,000 mg a day was safe but did not improve insulin sensitivity, glucose metabolism, resting energy expenditure or body composition⁷. The NMN trial found the clearest positive result: muscle insulin sensitivity and insulin signaling increased in women with prediabetes, measured by a clamp study⁸.

One of three trials showed a metabolic benefit, in one specific group. None of them measured energy or aging directly.

Seller claims against what was measured

If you are weighing NAD+ injections

Expect the lab value to move and treat everything else as untested. If you try an IV drip, go in knowing that the one published account of commercial NAD+ drips found every recipient had symptoms while the infusion ran. If a clinic quotes a study, ask whether it tested NAD+ itself, by the route you are buying, for the outcome you want.

Our NAD+ provider comparison lists the companies that sell it and counts how many of each one's claims a human trial actually supports.