NAD+ nasal spray is one of the newer forms of NAD+ delivery appearing on the supplement market. It is often promoted as a non-invasive alternative to injections and a potentially faster option than standard capsules. At the same time, it is currently one of the least studied methods of administering NAD+. The concept of intranasal administration itself has a scientific basis. The nasal cavity is highly vascularized, and some compounds can be absorbed relatively quickly through the nasal mucosa. However, this does not mean that the effective absorption of intact NAD+ via this route has been demonstrated.
The main limitation is simple: the number of human clinical trials involving nasal spray NAD+ is very small.
In this article, we explain what NAD+ nasal spray is, how nasal administration differs from injections and patches, what current research actually shows, and how to interpret the availability of such products in markets like the UK.
What is NAD+ nasal spray?
NAD+ nasal spray is a liquid preparation containing NAD+ or, in some products, an NAD+ precursor.
The preparation is sprayed into the nasal cavity using an applicator.
After spraying, the liquid contacts the nasal mucosa, which is the moist tissue lining the inside of the nose.
The goal is to enable the tissue to absorb the compound, bypassing the digestive tract.
Nasal drug delivery is a well-known method.
The nasal cavity contains a dense network of blood vessels and has a relatively thin absorption surface.
Because of this, some drugs can quickly enter the systemic circulation.
This route may also partially limit the first-pass effect in the liver, during which a portion of the orally administered compound may be metabolized or broken down before it enters the systemic circulation.
Several approved drugs already use this route of administration.
Examples include certain naloxone preparations used to treat opioid overdoses, sumatriptan used to treat migraines, and esketamine used to treat treatment-resistant depression.
These examples show that nasal administration can be very effective for appropriate molecules.
However, they do not prove that NAD+ behaves in the same way.
NAD+ is a much larger and more highly charged molecule than many intranasal medications.
These chemical differences are important because absorption through the nasal mucosa still depends on the size of the molecule, its charge, solubility, the composition of the formulation, and its interaction with the mucous membrane.
Therefore, the mere fact that intranasal administration works for other drugs should not be taken as proof that intact NAD+ is effectively absorbed through the nose.
How does NAD+ in a nasal spray differ from injections and patches?
Nasal sprays, injections, and transdermal patches share one common goal: to limit or completely bypass digestion in the gastrointestinal tract.
However, they achieve this in completely different ways.
NAD+ Injections and Intravenous Infusions
Intravenous administration delivers NAD+ directly into the bloodstream.
Once the compound enters the vein, there is no longer an absorption barrier.
Intramuscular injections deliver NAD+ to muscle tissue, while subcutaneous injections deliver it to the fatty tissue beneath the skin.
The compound must then still pass from these tissues into the bloodstream, but the digestive tract is completely bypassed.
These routes are therefore more direct than intranasal administration.
However, they require the use of a needle.
Intravenous administration usually takes longer and requires greater clinical supervision than using a nasal spray.
NAD+ Transdermal Patches
Transdermal patches work by allowing substances to penetrate the skin.
This creates a significant physical barrier, as the outer layer of the skin is specifically adapted to limit the penetration of molecules into the body.
NAD+ is a relatively large and highly polar molecule, which is why its passive diffusion through the skin is particularly difficult.
Some more advanced patch systems use technologies such as iontophoresis to enhance transport.
However, ordinary adhesive patches do not automatically provide the same degree of penetration.
NAD+ in a nasal spray
Intranasal administration uses the nasal mucosa rather than the skin.
The nasal mucosa is generally more permeable than the skin's outer barrier.
It is also well vascularized, allowing the appropriate molecules to enter the bloodstream relatively quickly.
However, it is still a selective biological membrane.
High molecular weight, strong charge, the properties of the formulation, mucociliary clearance, and enzymatic degradation may affect the amount of the substance that reaches the circulation.
In terms of absorption-related challenges, the intranasal route therefore falls somewhere between oral supplementation and direct injection.
It bypasses digestion in the gastrointestinal tract, but does not eliminate the need to pass through the biological membrane.
A Possible Nose-to-Brain Pathway
Intranasal administration also has one benefit that regular patches or oral capsules do not offer.
Some molecules may potentially reach the central nervous system via pathways associated with the olfactory and trigeminal nerves.
For this reason, intranasal administration generates special interest in neurological research.
Under certain conditions, it may allow for partial transport toward the brain without relying entirely on the conventional crossing of the blood-brain barrier.
This is a scientifically significant concept.
However, demonstrating nose-to-brain transport for a single compound does not mean it occurs just as effectively in the case of NAD+.
Direct pharmacokinetic studies specifically regarding NAD+ are still needed.
Does NAD+ nasal spray actually work?
Currently, there is insufficient human clinical trial data to state that commercial NAD+ nasal sprays reliably increase NAD+ levels or produce significant clinical effects.
Existing research is interesting, but it covers a much narrower scope than the claims often found in the marketing of these products.
What was actually investigated?
One of the studies most directly related to this topic focused on NAD+ in the context of olfactory disorders.
First, the scientists exposed cultured human olfactory epithelial stem cells to NAD+.
They observed that NAD+ promoted the differentiation of these cells into olfactory sensory neurons, as assessed by changes in the expression of neuronal markers. [1]
Next, the researchers moved on to an animal model.
Mice with chemically induced anosmia, which is the loss of sense of smell, were administered NAD+ intranasally.
Administration of the treatment was associated with a significant improvement in olfactory function and regeneration of the olfactory epithelium compared with untreated animals. [1]
This is significant experimental evidence.
The study directly examined intranasal NAD+, rather than relying solely on inferences based on oral supplementation or injections.
However, it is important to keep the proper context in mind.
The first part of the study involved human cells cultured in a laboratory.
The second part of the study was conducted on mice.
This was not a clinical trial involving humans.
The study also focused on olfactory tissue regeneration and olfactory disorders.
Energy, physical fitness, cognitive function, fatigue, slowing of aging, longevity, and overall well-being were not assessed.
These are completely different claims.
What kinds of human studies are missing?
No published controlled human study has been identified that tested a typical commercial intranasal spray containing NAD+ to determine whether it increases blood NAD+ levels.
There is also no robust data from human studies confirming an increase in NAD+ in brain tissue following the use of a commercial nasal spray.
Furthermore, the complete pharmacokinetic profile of intranasal NAD+, including the rate of absorption, peak concentration, elimination, and tissue distribution, has not been established.
Similarly, there are no reliable controlled human studies confirming benefits in terms of energy, cognitive function, recovery, slowing the aging process, or overall well-being.
For this reason, intranasal NAD+ is one of the least clinically characterized forms of NAD+ available on the market.
What can we conclude at this point?
The intranasal route is biologically justified.
There is also direct preclinical evidence indicating that intranasal NAD+ may affect olfactory tissue and olfactory-related functions in an animal model. [1]
That is reason enough to conduct further research.
However, this is not sufficient evidence of human efficacy.
The most accurate way to measure NAD+ in a nasal spray is currently an experimental delivery method still under development, rather than a clinically validated alternative to oral NR, NMN, injections, or intravenous NAD+.
Is NAD+ nasal spray available in the United Kingdom?
Products marketed as NAD+ nasal sprays can be found at certain online retailers of supplements and wellness products serving the British market.
However, commercial availability is not the same as the approval of a medicinal product.
NAD+ nasal sprays sold for wellness purposes have not undergone the same regulatory process as licensed prescription nasal medications.
In the United Kingdom, drugs are regulated by the Medicines and Healthcare products Regulatory Agency (MHRA).
The fact that a product is available online does not mean that the MHRA has evaluated and approved it for the treatment of fatigue, cognitive problems, age-related disorders, loss of smell, or other medical conditions.
A similar distinction applies to the whole of Europe.
Regulatory classification may depend on the product's composition, labeling, declared use, health claims made, and method of distribution.
Regulations may also change over time.
Therefore, when it comes to the British market, it is worth breaking it down into three separate questions.
The first question is whether a given product is available for purchase.
The second concerns whether it is legally offered within its current regulatory category.
The third point concerns whether the product has been clinically validated and approved as a drug.
Those are three different issues.
From the perspective of the quality of evidence, NAD+ in a nasal spray remains one of the least well-validated forms in the entire NAD+ category.
The concept itself is scientifically interesting.
However, direct clinical data in humans remain very limited.
NAD+ nasal spray vs other delivery methods
| Feature | NAD+ in a nasal spray | Oral NR/NMN | NAD+ Patches | NAD+ injection or IV |
|---|---|---|---|---|
| Main route of administration | Nasal mucosa | Gastrointestinal tract | Skin | Injection or directly into the bloodstream |
| Omija digestion | Yes | Not | Yes, if the substance is absorbed | Yes |
| Requires a needle | Not | Not | Not | Yes |
| Direct administration into the bloodstream | Not | Not | Not | IV: yes |
| The main barrier to absorption | Nasal mucosa | Alimentary tract and metabolism | Skin barrier | Minimum in the case of IV |
| Randomized human trials | Very limited | The strongest base among these forms | Very limited | Limited in wellness applications |
| Confirmed increase of NAD+ biomarkers in humans | It has not been clearly demonstrated | Yes to NR/NMN | No such effect has been demonstrated for standard patches | Limited data for commercial wellness protocols |
| A Potential Nose-to-Brain Pathway | Theoretically significant | No direct nasal passage | Not | Systemic route |
| Research on the sense of smell | Yes, preclinical [1] | This is not the main area of research | Not | This is not the main area of research |
| Proven effectiveness in overall wellness | Not | Increase in biomarkers confirmed; mixed clinical results | Not | Not |
The main advantage of intranasal administration is its convenience and the fact that it is a biologically sound route that bypasses digestion in the gastrointestinal tract.
The main drawback remains the lack of reliable pharmacokinetic and clinical data from human studies.
Frequently Asked Questions About NAD+ Nasal Spray
What is NAD+ nasal spray?
NAD+ nasal spray is a liquid product containing NAD+ or, in some preparations, its precursor, which is administered into the nose using an applicator. The aim is to enable absorption through the nasal mucosa while bypassing digestion in the gastrointestinal tract.
Does NAD+ in a nasal spray work?
There is not yet sufficient data from controlled human studies to confirm that commercial NAD+ nasal sprays reliably increase NAD+ levels in the blood or tissues or provide benefits in terms of overall well-being.
Preclinical studies have shown potentially interesting effects in human olfactory cells and in a mouse model of smell loss, but these results cannot be considered proof of efficacy in humans. [1]
Is NAD+ absorbed through the nose?
The nasal cavity can absorb many drugs, but the absorption of NAD+ in humans has not been adequately characterized.
NAD+ is a relatively large and highly charged molecule; therefore, direct pharmacokinetic studies are needed to determine what proportion of intact NAD+ crosses the nasal mucosa and enters the circulation.
Can NAD+ nasal spray reach the brain?
Intranasal administration may allow certain molecules to be transported toward the brain via pathways associated with the olfactory and trigeminal nerves.
However, controlled human studies have not demonstrated that NAD+ is effectively delivered to the brain in this way.
This remains a research hypothesis rather than a confirmed property of commercial nasal sprays.
Is NAD+ in a nasal spray better than capsules?
This has not been demonstrated.
Oral NR and NMN have a much larger body of randomized human studies, which have repeatedly demonstrated increases in NAD+-related biomarkers.
There is currently a lack of comparable data on nasal aerosols containing NAD+.
Is NAD+ in a nasal spray better than injections?
No direct human study has been conducted to demonstrate the superiority of intranasal NAD+ over injection or intravenous administration.
An aerosol avoids the need for a needle but still requires absorption through a biological membrane, whereas intravenous administration delivers NAD+ directly into the bloodstream.
Is NAD+ in a nasal spray better than NAD+ patches?
The nasal mucosa is usually more permeable than intact skin, so from a pharmacological point of view, nasal delivery of a large, charged molecule such as NAD+ may be more likely than passive transdermal delivery.
At the same time, neither standard NAD+ patches nor NAD+ nasal sprays currently have robust, controlled data from human studies confirming a reliable increase in systemic NAD+ levels.
Has NAD+ in a nasal spray been studied in cases of loss of smell?
Yes, but only at the preclinical stage in the study in question.
Scientists described the effects in cultured human olfactory cells and improvement in a mouse model of chemically induced anosmia following intranasal administration of NAD+.
However, the safety or efficacy of this method in treating olfactory disorders in humans has not yet been established. [1]
Is NAD+ nasal spray available in the United Kingdom?
Products sold as NAD+ nasal sprays are available from some vendors serving the UK market.
Commercial availability does not mean, however, that the product has been approved by the MHRA as a medicine.
Regulatory status depends on composition, declared properties, intended use, and current regulations in force in the UK.
Is NAD+ in a nasal spray approved by the MHRA?
NAD+ nasal spray is not an approved medicine authorized by the MHRA for the treatment of fatigue, aging processes, cognitive issues, olfactory disorders, or any other medical conditions.
Therefore, the wellness product available for sale in the UK should not be equated with the licensed pharmaceutical nasal spray.
Limitations of current research
The biggest limitation is the lack of controlled human studies.
The most directly related published study on intranasal NAD+ involved cultured human olfactory cells and a mouse model. [1]
Commercial aerosol has not been tested in humans.
The study also focused on olfactory disorders, rather than overall energy levels, recovery, cognitive function, longevity, or slowing the aging process.
A second limitation is the lack of accurate pharmacokinetic data in humans.
There is no well-established profile showing how much intranasally administered NAD+ enters the bloodstream, how quickly its concentration rises, what percentage remains chemically intact, how long it remains in circulation, or how much reaches specific tissues.
The potential nose-to-brain pathway also remains uncertain.
Intranasal administration of certain compounds may allow for specific transport to the central nervous system, but this mechanism cannot be automatically assumed for every molecule aerosolized in the nasal cavity.
Another limitation is the formulation itself.
Aerosols may differ in concentration, pH, excipients, preservatives, single-dose volume, droplet size, and other parameters affecting absorption and tolerability.
Therefore, results pertaining to a single experimental formulation cannot be automatically extrapolated to all commercially available products.
Finally, regulatory approval and clinical validation are two different matters.
The mere fact that NAD+ nasal sprays are available for purchase in certain markets does not mean that they have undergone the evaluation of quality, pharmacokinetics, safety, and efficacy required for an approved nasal medicinal product.
Current data therefore justify treating nasal spray NAD+ as an evolving delivery method with interesting preclinical results, but very limited direct human validation.
Disclaimer
This article is for educational and scientific-information purposes only. It does not constitute medical advice, treatment recommendations, dosage guidelines, administration methods, product selection, or a recommendation for the use of NAD+ nasal spray or any related product.
NAD+ nasal spray is not an FDA, EMA, or UK MHRA approved treatment, prevention method, or cure for any diseases, including olfactory disorders. The discussed research on the restoration of olfactory function was conducted on cultured human cells and animal models, and therefore should not be interpreted as evidence of the safety or efficacy of nasal NAD+ in treating loss of smell or other neurological disorders in humans.
Commercial availability should not be equated with confirmed systemic absorption, delivery to the brain, clinical efficacy, product quality, or regulatory approval. The human pharmacokinetics, long-term safety, optimal formulation, and clinically relevant effects of intranasally administered NAD+ remain insufficiently understood.
References
[1] Yoo, S. H., Jang, J. Y., Bae, J. S., Ventura, R., Kim, E. H., Kim, A. Y., Mo, J. H., Park, J., Kang, K., Yun, Y., Lee, J. H., Kim, Y. J., Lee, D. J., & Kim, J. H. (2026). Therapeutic effect of intranasal nicotinamide adenine dinucleotide in the restoration of olfactory dysfunction. Experimental & Molecular Medicine. https://doi.org/10.1038/s12276-026-01761-9