NAD+

People run it for a cluster of vague-but-appealing goals: more energy, sharper focus, a slowed-down clock (“anti-aging”), and — a big one in this corner — support during addiction and alcohol recovery. The delivery methods are the tell that this is community territory: long IV infusions (often hours, and frequently uncomfortable), SubQ shots, or intranasal spray. What it actually is, though, is not a drug with a target — it’s a coenzyme your cells already use by the billion every second. The leap from “this molecule is essential” to “injecting more of it makes you feel amazing” is exactly the leap the evidence hasn’t made.

The genuinely interesting part is the biology, not the vial. NAD+ sits at the center of two stories: it shuttles electrons through the reactions that turn food into ATP (the redox role every textbook covers), and it’s the required fuel for the sirtuins and PARPs — the enzymes tied to DNA repair and the “longevity” narrative. NAD+ levels measurably decline with age, which is the seed of the whole anti-aging pitch. But here’s the distinction the marketing blurs: the human evidence that you can meaningfully move the needle is on oral PRECURSORS — nicotinamide riboside (NR) and NMN — which the body converts into NAD+. Raising NAD+ with a precursor pill is a different thing from injecting the finished coenzyme, and the precursor data does not transfer to the IV drip.

NAD+ is a coenzyme central to cellular energy and redox: it cycles between NAD+ and NADH to carry electrons through glycolysis, the TCA cycle, and oxidative phosphorylation — the machinery that makes ATP. Separately, it’s consumed as a co-substrate by the sirtuins (NAD+-dependent deacylases linked to metabolic and stress signaling) and by PARPs in DNA repair, which is the mechanistic basis for the longevity framing. The open question for injected NAD+ is delivery: intact NAD+ is a large, charged molecule with poor cellular uptake, and much of an oral or IV dose is broken down to precursors before cells can use it — which is part of why precursor supplementation (NR/NMN) is the route with actual human pharmacokinetic data behind it. Treat any precise claim about what injected NAD+ does inside a cell as ahead of the evidence.

The defining side effects are infusion-driven and rate-dependent: flushing, chest or throat tightness, a pressure sensation, abdominal cramping, lightheadedness, and nausea — classically when the drip is run too fast, easing when it’s slowed. This is why the infusions are long and often described as uncomfortable rather than relaxing. SubQ use can cause injection-site irritation. Short-term tolerability in small real-world and pilot reports looks acceptable when administered carefully, but that’s a thin basis: there is no robust long-term safety characterization for the way the community uses injected NAD+, and “no serious problems reported in small studies” is not the same as proven safety.

In community practice it’s framed as a foundational “run-everything-better” cofactor rather than a targeted add-on, so it’s loosely paired with whatever someone is already chasing — recovery, energy, or longevity stacks. The more evidence-honest pairing is conceptual: oral precursors (NR/NMN) are the route with human PK data, so people serious about actually raising NAD+ often lean there instead of, or alongside, the drip. None of the injectable combinations rest on trial evidence — they’re routines built around a shared goal, not data.