Nasal sprays are sold on one specific idea: a direct route from the nose to the brain that skips the bloodstream entirely. That pathway is real and genuinely interesting. The evidence that NAD+ precursors use it to any meaningful degree is not there.

Short version

Intranasal delivery has a legitimate research basis for some compounds. For NAD+ precursors it is currently an extrapolation, not a finding. We would not pay a premium for it today.

The idea behind it

The roof of the nasal cavity carries olfactory nerve endings that connect more or less directly to the brain, and it also sits close to branches of the trigeminal nerve. In principle a molecule deposited high in the nose can travel along those routes into the central nervous system without passing through general circulation or crossing the blood-brain barrier in the usual way.

This is not fringe. Nose-to-brain delivery is an active research area, and some compounds are delivered intranasally for exactly this reason.

Why that does not transfer automatically to NAD+

  • Deposition is the hard part. The olfactory region is a small patch high in the nasal cavity. Ordinary sprays deposit most of their volume lower down, where the compound is simply absorbed into local blood vessels or swallowed.
  • Molecular fit still applies. The nose-to-brain route is not a loophole around chemistry. NAD+ is large and charged; precursors are better but still not ideal candidates.
  • The doses are small. A spray delivers a fraction of what an oral product does. Even with a favourable route, the absolute amount is limited.
  • Specific human evidence is lacking. The gap between "this pathway exists" and "this product uses it" is where most of the marketing lives.
A fair point in its favour. Absence of evidence is not evidence of absence. Intranasal NAD+ may turn out to do something useful. We will say so if the work gets done. Right now the claims run well ahead of the data, and the pricing does not reflect that uncertainty.

What you are likely getting

For most nasal NAD+ products, the realistic outcome is a small dose absorbed through nasal tissue into the bloodstream — which is a legitimate route, just not the one on the label — plus some portion swallowed and handled like a very small oral dose, at a price per milligram well above capsules.

Our position

If you are curious and the cost is immaterial to you, it is not harmful to try. If you are building a routine you intend to sustain, put the money into a format with evidence behind it and reassess nasal delivery in a few years.

Last reviewed: 3 October 2026.

Related: Oral capsules · Sublingual · All six formats