NAD+ injections and infusions: Category 1 status, and the evidence that is not there

NAD+ is not a peptide. It is on this site because the clinics that sell peptide injections sell NAD+ injections and drips from the same menu, and because its regulatory status is the one thing on that menu that is different in a way customers rarely understand.

What it is

Nicotinamide adenine dinucleotide is a coenzyme present in every cell, cycling between NAD+ and NADH to carry electrons in energy metabolism and serving as a substrate for sirtuins, PARPs and CD38. Cellular NAD+ declines with age in animal studies and in some human tissues. That observation launched a supplement industry built on oral precursors (nicotinamide riboside, nicotinamide mononucleotide) and a clinic industry built on injecting or infusing NAD+ itself.

The evidence

Infused or injected NAD+. One published human study we can find: a 2019 pilot (PubMed 31572171) in which healthy volunteers received a six-hour intravenous infusion while plasma and urine NAD+ metabolites were sampled. Plasma NAD+ did not rise above baseline until about two hours into the infusion, and the study characterised where the infused molecule went. No control group, no clinical endpoint, no follow-up. That is the interventional human literature on the product clinics actually deliver.

Oral precursors. Nicotinamide riboside has randomised, placebo-controlled trials. A 2018 crossover study in 24 middle-aged and older adults (PubMed 29599478) found six weeks of supplementation raised blood NAD+ and was well tolerated. Clinical outcomes in that and later trials were modest or absent. A 2026 systematic review (PubMed 41655607) summarises the field. These are studies of a different molecule by a different route; they are shown for context, not counted toward the grade.

Regulatory status

FDA's 503A category list document (updated May 14, 2026) places "Nicotinamide Adenine Dinucleotide (NAD)" and "Nicotinamide Adenine Dinucleotide Disodium Reduced (NADH)" in Category 1. FDA's definition: substances that may be eligible for the 503A bulks list, nominated with sufficient information for FDA to evaluate, and not on any other list; FDA "does not intend to take action against a compounder for compounding drugs using bulk drug substances listed in category 1, provided that the conditions described in the guidance document are met."

That is a materially different position from every research peptide on this site, and it is also much less than the word "legal" implies. Category 1 is a statement about FDA's enforcement intentions during evaluation. It is not a finding that NAD+ is safe or effective for anything, it does not create an approved product, and FDA can move a substance out of Category 1 when it identifies a safety concern, which is exactly what happened to the peptides on the Category 2 page. The same document lists "Beta-Nicotinamide Adenine Dinucleotide Disodium Salt Trihydrate" in Category 3, nominated without adequate support.

There is no FDA-approved NAD+ drug product.

Safety signals

FDA has published no Category 2 concern for NAD+. Clinics describe infusion-rate symptoms, chest tightness, nausea, cramping, that resolve when the drip is slowed; we found no controlled study that quantifies them and do not cite anecdote as data. A sterile injectable made by a compounding pharmacy carries the usual compounding risks the pharmacy vetting checklist is built to surface.

Grade: D

D because no controlled human study of injected or infused NAD+ exists for any use. No X flag, because FDA has published no specific safety concern. Category 1 status and grade D are not in tension: one describes enforcement policy, the other describes evidence. Holding both in mind at once is the skill this site is trying to teach.