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 very concept of intranasal administration has a scientific basis. The nasal cavity is highly vascularised, and certain compounds can be absorbed relatively quickly through the nasal mucosa. However, this does not mean that 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 such as the UK.
What is NAD+ in a nasal spray?
NAD+ nasal spray is a liquid preparation containing NAD+ or, in some products, an NAD+ precursor.
The preparation is sprayed in the nasal cavity using an applicator.
After spraying, the liquid comes into contact with the nasal mucosa, which is the moist tissue lining the inside of the nose.
The objective is to enable the compound to be absorbed by this tissue, bypassing the gastrointestinal tract.
Intranasal administration of medicines 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 medicines can quickly pass into the systemic circulation.
This drug can also partially reduce the first-pass effect through the liver, during which part of an orally administered compound may be altered or broken down before reaching the systemic circulation.
Several approved medicines already use this route of administration.
Examples include certain naloxone preparations used to treat opioid overdoses, sumatriptan used to treat migraine, and esketamine used to treat treatment-resistant depression.
These examples show that intranasal administration can be highly effective for suitable 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 medicines.
These chemical differences are significant because absorption through the nasal mucosa still depends on the size of the molecule, its charge, its solubility, the composition of the preparation and its interaction with the mucous membrane.
Therefore, the mere fact that intranasal administration is effective for other drugs should not be taken as evidence 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 all have one common aim: 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 has entered the vein, there is no longer any absorption barrier.
Intramuscular injections deliver NAD+ to muscle tissue, whilst 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 do require the use of a needle.
Intravenous administration also usually takes longer and requires closer clinical monitoring than the use of a nasal spray.
NAD+ transdermal patches
Transdermal patches work by allowing substances to pass through the skin.
This creates a significant physical barrier, as the outer layer of the skin is specifically designed to limit the passage 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 delivery.
However, ordinary adhesive plasters do not automatically provide the same level of permeability.
NAD+ in a nasal spray
Nasal 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 supplied with blood, which means that the relevant molecules can 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 all affect the amount of the substance that enters the bloodstream.
In terms of the difficulties associated with absorption, the nasal route therefore lies 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–brain pathway
Intranasal administration also has one advantage that ordinary 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 is of particular interest in neurological research.
Under certain conditions, it may allow for partial transport towards the brain without relying entirely on the conventional crossing of the blood–brain barrier.
This is a scientifically significant concept.
Demonstrating nose-to-brain transport for a single compound does not, however, mean that it occurs equally effectively in the case of NAD+.
Direct pharmacokinetic studies specifically on NAD+ are still needed.
Does the NAD+ nasal spray actually work?
Currently, there are too few human trial data to state that commercial NAD+ nasal sprays reliably increase NAD+ levels or induce significant clinical effects.
Existing research is interesting, but it covers a significantly narrower scope than the claims frequently found in the marketing of these products.
What was actually investigated?
One of the most directly related studies on this subject concerned 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 sensory neurons of the olfactory system, as assessed by changes in the expression of neuronal markers. [1]
The researchers then moved on to an animal model.
Mice with chemically induced anosmia, i.e. a loss of the sense of smell, were administered NAD+ intranasally.
Administration of the treatment was associated with a significant improvement in olfactory function and the regeneration of the olfactory epithelium compared with untreated animals. [1]
This is crucial experimental evidence.
The study directly examined intranasal NAD+, rather than merely drawing conclusions based on oral supplementation or injections.
However, the proper context must be maintained.
The first part of the study involved human cells cultured in the laboratory.
The second part of the study was carried out on mice.
It was not a clinical trial involving human subjects.
The study also focused on olfactory tissue regeneration and olfactory disorders.
Energy levels, physical fitness, cognitive function, fatigue, the slowing of the ageing process, longevity and general well-being were not assessed.
These are completely different claims.
What kind of human studies are lacking?
No published controlled human trial has been identified in which a typical commercial intranasal spray containing NAD+ has been tested to see whether it increases blood NAD+ levels.
There is also no strong human trial data confirming an increase in NAD+ in brain tissue following the use of a commercial nasal spray.
The full pharmacokinetic profile for intranasal NAD+, including absorption rate, maximum concentration, elimination, and tissue distribution, has also not been established.
Similarly, there are no reliable controlled human trials confirming benefits in terms of energy levels, cognitive function, recovery, slowing down the ageing process or general well-being.
For this reason, intranasal NAD+ is one of the least well-characterised clinically available forms of NAD+ on the market.
What can be stated at present?
The intranasal route is biologically justified.
There is also direct preclinical evidence suggesting that intranasal NAD+ may affect the olfactory tissue and olfactory-related functions in an animal model. [1]
That is reason enough to carry out further research.
However, this is not sufficient evidence of its effectiveness in humans.
The most accurate way of measuring 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 UK?
Products marketed as NAD+ nasal sprays can be found at certain online retailers of supplements and wellness products serving the UK market.
However, being available on the market is not the same as a medicinal product being authorised.
NAD+ nasal sprays sold for wellness purposes have not undergone the same regulatory process as licensed prescription nasal medicines.
In the UK, medicines 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 assessed it and authorised it for the treatment of fatigue, cognitive problems, age-related disorders, loss of smell or any other medical conditions.
A similar distinction applies across Europe.
Regulatory classification may depend on the product’s composition, labelling, declared use, health claims made and method of distribution.
Regulations can also change over time.
Therefore, when it comes to the UK market, it is worth distinguishing between three separate issues.
The first concerns whether a particular product is available to buy.
The second point concerns whether it is lawfully offered within its current regulatory category.
The third point concerns whether the product has been clinically validated and authorised as a medicinal product.
These are three different issues.
From the point of view of the quality of the evidence, NAD+ in nasal spray remains one of the least well-validated forms within the entire NAD+ category.
The very concept is scientifically interesting.
However, direct clinical data in humans remain very limited.
NAD+ nasal spray versus other delivery methods
| Feature | NAD+ in a nasal spray | Oral NR/NMN | NAD+ patches | NAD+ injection or IV |
|---|---|---|---|---|
| Main route of administration | Nasal mucosa | alimentary canal | Skin | Injection or directly into the bloodstream |
| It bypasses the digestive system | Yes | Not | Yes, if the substance is absorbed | Yes |
| Needs a needle | Not | Not | Not | Yes |
| Direct administration into the bloodstream | Not | Not | Not | IV: yes |
| Main absorption barrier | Nasal mucosa | Gastrointestinal tract and metabolism | Skin barrier | Minimum in the case of IV |
| Randomised human trials | Very limited | The strongest base among these forms | Very limited | Limited in wellness applications |
| Confirmed increase in NAD+ biomarkers in humans | It has not been clearly demonstrated | Yes to NR/NMN | No evidence has been provided for standard plasters | Limited data for commercial wellness protocols |
| A potential nose–brain pathway | Theoretically significant | No direct nasal passage | Not | Systemic route |
| Research into the sense of smell | Yes, preclinical [1] | This is not a main area of research | Not | This is not a main area of research |
| Proven effectiveness in general wellness | Not | Increase in biomarkers confirmed; mixed clinical results | Not | Not |
The main advantage of intranasal administration is convenience and the fact that it is a physiologically appropriate route which bypasses digestion in the gastrointestinal tract.
The main drawback remains the lack of robust pharmacokinetic and clinical data in humans.
Frequently asked questions about NAD+ nasal spray
What is NAD+ in a nasal spray?
NAD+ nasal spray is a liquid product containing NAD+ or, in some formulations, its precursor, which is administered into the nose using an applicator. The aim is to allow absorption through the nasal mucosa whilst bypassing digestion in the gastrointestinal tract.
Does NAD+ in a nasal spray work?
There is not yet sufficient data from controlled human trials to confirm that commercial NAD+ nasal sprays reliably increase NAD+ levels in the blood or tissues, or that they confer any benefits in terms of general 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 taken as 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 characterised.
NAD+ is a relatively large and strongly charged molecule, which is why direct pharmacokinetic studies are needed to determine how much intact NAD+ crosses the nasal mucosa and enters the circulation.
Can NAD+ in a nasal spray reach the brain?
Intranasal administration may enable certain molecules to be transported towards the brain via pathways associated with the olfactory and trigeminal nerves.
However, controlled human trials have not demonstrated that NAD+ is effectively delivered to the brain in this way.
This remains a research hypothesis rather than a proven 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 randomised human trials, 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 study has been conducted in humans 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 generally more permeable than intact skin; therefore, from a pharmacological point of view, intranasal delivery of a large, charged molecule such as NAD+ may be more likely than passive delivery through the skin.
At the same time, neither standard NAD+ patches nor NAD+ nasal sprays are currently supported by robust, controlled data in humans confirming a reliable increase in systemic NAD+ levels.
Has intranasal NAD+ been studied for loss of smell?
Yes, but only at the pre-clinical stage in the study in question.
Scientists have described the effects in cultured human olfactory cells and the 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 UK?
Products sold as NAD+ nasal sprays are available from some retailers serving the UK market.
Commercial availability does not mean, however, that the product has been approved by the MHRA as a medicinal product.
The regulatory status depends on the composition, declared properties, intended use and current regulations in force in the UK.
Is NAD+ nasal spray approved by the MHRA?
NAD+ nasal spray is not a recognised medicine approved by the MHRA for the treatment of fatigue, ageing 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 a licensed pharmaceutical nasal spray.
Limitations of current research
The biggest limitation is the lack of controlled studies involving humans.
The most directly related published study on intranasal NAD+ involved cultured human olfactory cells and a mouse model. [1]
It has not been tested as a commercial aerosol in humans.
The study also focused on olfactory disorders, rather than general energy levels, recovery, cognitive performance, longevity, or slowing down ageing.
Another limitation is the lack of exact human pharmacokinetic data.
There is no well-established profile showing how much intranasally administered NAD+ enters the bloodstream, how quickly its concentration rises, what proportion remains chemically intact, how long it persists in the circulation, or how much reaches individual tissues.
The potential nose-to-brain pathway also remains uncertain.
Intranasal administration of certain compounds may enable specific transport to the central nervous system, but this mechanism cannot be automatically assumed for every molecule nebulised in the nasal cavity.
Another limitation is the formulation itself.
Aerosols may vary in terms of concentration, pH, excipients, preservatives, single-dose volume, droplet size and other parameters that affect absorption and tolerability.
Results for a single experimental preparation therefore cannot be automatically applied to all commercially available products.
Finally, regulatory approval and clinical validation are two different matters.
The mere fact that NAD+ nasal sprays can be bought on some markets does not mean that they have undergone the quality, pharmacokinetic, safety and efficacy assessment required for an authorised medicinal product for nasal use.
Current data therefore justify treating NAD+ nasal spray as an emerging 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+ in a nasal spray is not a treatment, preventative method or cure for any diseases, including smell disorders, approved by the FDA, the EMA or the UK’s MHRA. The studies discussed regarding the restoration of olfactory function were conducted on cultured human cells and animal models; therefore, they should not be interpreted as evidence of the safety or efficacy of intranasal NAD+ in the treatment of loss of smell or other neurological disorders in humans.
Commercial availability should not be equated with confirmed systemic absorption, brain delivery, clinical efficacy, product quality, or regulatory approval. Human pharmacokinetics, long-term safety, optimal formulation, and the 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