What is the difference between NMN and NAD+?

This guide compares NMN, NR and NAD+ using primary sources: what each is, how each has been given in human studies and what those studies found.

We do not sell supplements or link to products, and nothing here is a recommendation.

What is the difference between NMN and NAD+?

NAD+ is the coenzyme itself, while NMN (nicotinamide mononucleotide) is a precursor, an intermediate that has been studied as a way of raising NAD+ in the body.

NAD+ is “a coenzyme for redox reactions, making it central to energy metabolism” ¹.

Nicotinamide riboside (NR) and NMN are the two NAD+ intermediates that have been studied most ².

They are different molecules from NAD+, so results for one cannot be assumed for another.

Our guide to what NAD+ is has the background.

NMN vs NR vs NAD+: how do they compare?

They differ in what they are, how they have been given in human studies and how much outcome evidence exists.

	NAD+	NMN	NR
What it is	The coenzyme 1	A precursor (intermediate) 2	A precursor (intermediate) 2
How given in the human studies we cite	By IV infusion in a pilot of 11 healthy men 3	By mouth in the trials we cite, for example 250 mg a day for 12 weeks 4; by IV in one open-label safety study of 10 healthy volunteers 5	By mouth, for example 1 g a day for 21 days in 12 aged men 6
Effect on NAD+ measures	Infused NAD+ was rapidly and completely removed from plasma at the study rate for the first two hours 7	Oral NMN consistently raised NAD-related metabolites across the studies in a 2026 systematic review 8	Oral NR raised NAD+ in healthy middle-aged and older adults in a 6-week crossover trial 9
Outcomes trials	None found for IV or intramuscular NAD+ for ageing or wellness 8	Mixed results (see below)	Mixed results (see below)

No published trial we found compares injected NAD+ with oral NMN or NR for any health outcome, based on our searches and the two 2026 reviews ¹⁰.

Is NAD+ absorbed when taken by mouth?

We did not find a primary source we can cite on how well NAD+ itself is absorbed when swallowed, so we do not state an answer.

What we can say is narrower: the oral human trials we cite tested precursors, namely NR, NMN, nicotinic acid and nicotinamide, not NAD+ itself ^8, 11.

When NAD+ was infused into a vein, it was rapidly and completely removed from plasma at the study’s rate for at least the first two hours, and that result is about infusion, not swallowing ⁷.

If you are weighing the two, it is reasonable to ask a pharmacist or doctor what is known about the specific product.

What does research show about NMN and NR in people?

In a 2026 systematic review, oral NMN and NR consistently raised NAD-related measures and were generally well tolerated over weeks to months, but effects on health outcomes were mixed and often null.

The same review found effects on functional, metabolic, vascular and other outcomes to be “heterogeneous and often null or endpoint-specific” ⁸.

A 2025 review in Nature Metabolism likewise says human trials of NAD+ precursors “have shown limited efficacy” ¹².

A review of oral compounds that raise NAD+ adds that small sample sizes limit interpretation of physiological outcomes ¹³.

The table lists individual oral trials; none of them tested injected NAD+.

Trial	Who and what	What it reported
Kim et al., 2022 (oral NMN)	108 older Japanese adults, 250 mg a day for 12 weeks	Improved lower-limb function and reduced drowsiness 4
Liao et al., 2021 (oral NMN)	48 amateur runners, 6 weeks	Higher aerobic-capacity measures in medium and high dose groups, but no difference in VO2max, O2-pulse or peak power 14
Yoshino et al., 2021 (oral NMN)	Postmenopausal women with prediabetes who were overweight or obese, 10 weeks	Increased muscle insulin sensitivity in this one population 15
Orr et al., 2024 (oral NR)	20 older adults with mild cognitive impairment, placebo-controlled	Well tolerated and did not alter cognition 16
Wu et al., 2025 (oral NR)	58 people with long COVID, randomised and placebo-controlled	No significant difference in fatigue severity or cognitive outcomes; high dropout 17

Each result applies to its own population and dose, and none should be read across to injected NAD+.

Our guide to what the evidence says covers claimed uses of NAD+ in more detail.

Are NMN supplements legal to sell in the UK?

We could not verify the UK authorisation status of NMN or NR as food-supplement ingredients from a primary source, so we do not state it.

This is a gap in our evidence, not a finding that they are or are not allowed.

What the rules we have verified do say is that a substance presented as having properties of preventing or treating disease in human beings can be a medicinal product ¹⁸.

The MHRA says you cannot advertise any medicine that is not licensed by the MHRA ¹⁹.

Claims also need evidence: in February 2026 the ASA upheld a complaint about an NAD+ skin patch, finding its claims about energy, focus, memory and ageing were not substantiated, and noting that the trials relied on used oral NMN, not the product (ruling A25-1310978) ²⁰.

The ASA’s expert advice is that oral-supplement evidence can support claims for an IV product only in limited ways, and that evidence on regular supplementation is unlikely to support a one-off infusion ²¹.

Our guide to UK regulation covers the injectable side.

NAD+ injections vs oral supplements: what are the practical differences?

The main differences are who may supply and administer the product, what is known about reported effects and how little head-to-head evidence exists.

	NAD+ by injection or IV	Oral NMN or NR
Who may give it	If the product is a prescription-only medicine, an appropriate practitioner or someone acting on their directions 22	We did not verify the UK rules for oral supplements
Reported effects in studies	IV NAD+: nausea, abdominal discomfort, flushing, cramping and chest pressure, particularly at faster infusion rates; long-term safety not known 23	Generally well tolerated over weeks to months 8
Outcome evidence	No outcomes trials of IV or intramuscular NAD+ for ageing or wellness 8	Heterogeneous, often null 8
Clinic price, median, as displayed on clinic websites on 11 November 2026	IV £300 (n = 36 price points, 22 providers); injection £90 (n = 10 price points, 10 providers) 24	Not covered

Our guides to NAD+ injections and NAD+ IV therapy cover the clinic routes.

What could I ask a pharmacist or doctor?

You could ask what evidence supports a product for your goal, whether it is a licensed medicine, and what is known about long-term safety.

• What human evidence is there for this product and my goal, and was it tested on the same product and route? ²¹
• Is this a licensed medicine, an unlicensed product or a food supplement? ¹⁸
• What is known about its long-term safety, and what is not known? ²⁵
• How might it fit with my health conditions and any medicines I take? The NMC says prescribers need enough knowledge of your health and your full medical and prescribing history ²⁶.
• Is there anyone independent I can ask, such as my GP? ²⁷

This page is general information, not medical advice. Speak to your GP, pharmacist or a registered prescriber before deciding anything about NAD+, NMN or NR, and read our medical disclaimer.

It was drafted with AI assistance from a fact-pack of primary sources by the NAD Injections editorial team and has not been clinically reviewed.