NAD+ Explained: Injections, Drops and Nasal Sprays

If you've spent any time reading about longevity programs, you've probably seen NAD+ offered three different ways: an injection, drops you hold under your tongue, or a nasal spray. The marketing around each form can make them sound like different products. They aren't. NAD+ is one molecule, and the delivery method is really a question about how it gets into your body, not what it is.

What NAD+ actually is

NAD+, short for nicotinamide adenine dinucleotide, is a coenzyme every cell in your body uses to run basic metabolic work: converting food into usable energy and supporting the cellular repair processes that run in the background all day. It isn't a hormone, a drug class of its own, or something exotic. Some research reports that NAD+ levels measured in blood or tissue tend to decline with age, which is part of why the compound gets attention in longevity contexts. That's a correlation researchers are still working to explain, not a settled account of what raising NAD+ does for a person.

Why the delivery form is a logistics question, not a different compound

An injection, sublingual drops, and a nasal spray are three ways of trying to get NAD+ past the digestive system, which tends to break the molecule down before much of it reaches the bloodstream intact. Injecting it bypasses digestion entirely. Drops held under the tongue and nasal sprays are attempts to absorb some of the compound through mucous membranes instead of swallowing it. In principle, that changes how much reaches circulation and how fast. In practice, the research comparing these routes head to head in humans is thin, so most of what gets said about one form being "more effective" than another is closer to a plausible mechanism than a demonstrated result. Programs that offer more than one form, like the injection, drops, and spray options Luvo Health lists for its longevity program, generally leave the choice of form to a licensed provider during the evaluation rather than to the person doing the reading.

What the research actually covers

This is the part worth being direct about: most of the published human research on raising NAD+ levels has studied oral precursor compounds, not injectable or intranasal NAD+ itself. Nicotinamide riboside, an NAD+ precursor taken as a capsule, is the most-studied version. In one randomized, placebo-controlled trial of 140 healthy overweight adults, daily doses of nicotinamide riboside raised blood NAD+ within two weeks, with the increase getting larger at higher doses, and adverse events were similar to placebo over eight weeks. A separate trial in 120 adults aged 60 to 80 found comparable results with a combination supplement, again over eight weeks, again with no serious adverse events reported. Both trials looked at NAD+ levels rising in blood, not at injectable or nasal delivery, and both ran for two months, which says little about what happens over a year or more. If a program's marketing cites NAD+ research to describe what its injection or spray does, it's worth asking which delivery form the underlying study actually used.

Where compounded NAD+ fits into the regulatory picture

Prescription NAD+ offered through a longevity program is typically a compounded medication, meaning it's prepared by a licensed pharmacy or provider rather than mass-manufactured and separately approved as its own drug product. The FDA is explicit that compounded drugs are not FDA-approved, since the agency does not independently verify the safety, effectiveness, or quality of a compounded preparation before it reaches a patient the way it does for an approved drug. That's true of an injectable, drops, or a spray version alike. Compounded; not FDA-approved. Prescription required only if a licensed provider finds it appropriate.

That's also why programs offering NAD+ route people through a telehealth evaluation first, rather than selling it as an over-the-counter supplement. Health Stacker's peptide guide collection walks through how NAD+ and similar compounds get evaluated and prescribed, and what questions are worth asking before choosing a delivery form. What any one person notices after starting a program is not something a published trial can tell you in advance; individual results vary, and no program can promise a particular outcome.

What to actually compare

If you're weighing an injection against drops or a spray, the honest comparison isn't which one "works better" in some general sense. It's absorption plausibility (injectable bypasses digestion most directly), convenience (drops and sprays don't require needles), and what a licensed provider recommends given your situation after an evaluation. None of the three forms changes what NAD+ is or turns it into a treatment for a disease. If you want a longevity program to spell out exactly how its NAD+ is compounded, dosed, and delivered, the Luvo Health longevity program page lays out the injection, drops, and nasal spray options it offers through a licensed provider evaluation.

Sources

• Airhart et al., "Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride)," PLOS ONE, 2019, https://pmc.ncbi.nlm.nih.gov/articles/PMC6611812/. 140 healthy overweight adults, oral nicotinamide riboside 100/300/1,000 mg/day, 8 weeks randomized double-blind placebo-controlled, dose-dependent NAD+ increase with no significant adverse-event difference vs. placebo, limited to an oral precursor and a short duration.
• Dellinger et al., "Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably," npj Aging and Mechanisms of Disease, 2017, https://pmc.ncbi.nlm.nih.gov/articles/PMC5701244/. 120 adults aged 60-80, oral NR plus pterostilbene vs. placebo, 8 weeks randomized double-blind placebo-controlled, dose-dependent NAD+ increase with no serious adverse events, again an oral precursor rather than injectable or nasal NAD+.
• U.S. Food and Drug Administration, "Compounding and FDA: Questions and Answers," https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers. Regulatory description of compounded drugs including sterile injectables, states compounded drugs are not FDA-approved and are not independently verified for safety, effectiveness, or quality before reaching a patient. A regulatory description, not evidence of effectiveness for any specific delivery form.

Educational content only. Not medical advice, diagnosis, or treatment. Talk to a licensed clinician before starting, changing, or stopping any medication, peptide, or supplement.