NAD+ Supplements and Injections: What the Human Trials Show

NAD+ is a coenzyme, not a peptide, so “NAD peptide” is a misnomer. Supplements made of its precursors, NR and NMN, reliably raise NAD+ in the blood. Whether that improves health is a different question, and human trials so far show inconsistent or no benefit. No outcome trial has tested NAD+ injections or IV drips for anti-aging or wellness.

What Is NAD+?

NAD+ is a coenzyme found in every cell. It is not a chain of amino acids, so it is not a peptide. NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide) are precursors your cells convert into NAD+. Most trials test these oral precursors.

Do NR And NMN Raise NAD+ Levels?

Yes. In a 2025 randomized trial in long COVID, 2,000 mg a day of NR raised blood NAD+ 2.6 to 3.1 times. In a 2017 trial of 120 healthy adults aged 60 to 80, a combination of NR and pterostilbene raised whole-blood NAD+ about 40% at the recommended dose and about 90% at double the dose after 4 weeks. Its authors are affiliated with Elysium Health, which sells the product.

Do NAD+ Supplements Improve Health?

The evidence is mixed. A 2026 systematic review of 113 studies (33 in humans) found that oral NR and NMN reliably raise NAD-related markers and are generally well tolerated. Effects on function and metabolic health were inconsistent, often null, or limited to specific outcomes. It called the clinical case for anti-aging or wellness inconclusive.

• Long COVID (NR): in 58 people, NR did not beat placebo on cognition, fatigue (p=0.59), sleep (p=0.69), anxiety or depression. Exploratory within-group changes appeared, but they were not adjusted for multiple testing. About half the NR group dropped out by week 20. Niagen Bioscience, which sells NR, was a funder.
• Parkinson’s (NR): in the NADPARK phase I trial of 30 newly diagnosed patients, 1,000 mg a day for 30 days raised brain NAD in some of them. Mild clinical improvement was associated with a rise in brain NAD. It was a safety trial, not proof of benefit.
• Prediabetes (NMN): a 10-week randomized trial in postmenopausal women with prediabetes who were overweight or obese found NMN improved muscle insulin sensitivity. It is one trial in one group, not a finding for older adults in general.
• Metabolic health (NMN): a 2026 meta-analysis of 15 randomized trials found no significant effect on body weight, BMI, fasting glucose, HbA1c, lipids or systolic blood pressure, Diastolic blood pressure fell slightly. The authors found no broad metabolic benefit.
• Ataxia telangiectasia (NR): a small open-label study with no placebo group reported better coordination and eye movements. It needs a controlled trial.

Do NAD+ Injections Or IV Drips Work?

Nobody knows. The 2026 review found no eligible outcome trials of intravenous or intramuscular NAD+ itself for anti-aging or wellness. No human dose has been validated, and NAD+ injections are not FDA-approved for those uses. This page does not list doses, schedules or injection sites.

Are NR And NMN Safe?

In trials lasting weeks to months, oral NR and NMN were generally well tolerated. The NMN meta-analysis found no significant rise in overall, serious or withdrawal-related adverse events. Those trials were short. Long-term safety is not established. If you have cancer, are pregnant or breastfeeding, or take medicine, talk to a clinician first.

Is NMN Legal?

FDA reversed its earlier position in September 2025 and concluded that NMN is not excluded from the definition of a dietary supplement. That means NMN can be sold as a supplement. It does not mean the products are tested or that they work.

Are NR Supplements Mislabeled?

ChromaDex, the company behind the NR brand Tru Niagen, bought 39 NR products in the US and reported that 13% met their label claims. Five met them and five more came within 90% to 99%. Tru Niagen was one of the five that met the claim. This is a seller’s test of its competitors, and the company says liposomal products were particularly problematic. It shows why independent lab reports matter.

How Do You Check A Supplement?

• A certificate of analysis for your lot, from an independent lab you can look up.
• Verification of the active ingredient amount, not only purity.
• Testing for heavy metals and microbes.
• Named precursors on the label, such as nicotinamide riboside or nicotinamide mononucleotide.

See our fake peptide vendors list for how lab-report fraud works, and our vendors ranked by lab-report evidence.

Bottom Line

NR and NMN raise NAD+ in blood. Human trials have not shown clear benefits for fatigue, cognition or metabolic health, and injections and IVs have no outcome trials at all. Treat NAD+ products as unproven.

References

• Nicotinamide riboside in long COVID: effects on NAD+ levels, cognition and symptom recovery, a randomized controlled trial. EClinicalMedicine. 2025;89. PMID 41357333.
• Dellinger RW, et al. Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably. NPJ Aging Mech Dis. 2017. PMID 29184669.
• NAD+ supplementation for anti-aging and wellness: a PRISMA-guided systematic review of preclinical and clinical evidence. Ageing Res Rev. 2026;116. PMID 41655607.
• Brakedal B, et al. The NADPARK study: a randomized phase I trial of nicotinamide riboside supplementation in Parkinson’s disease. Cell Metab. 2022;34:396-407. PMID 35235774.
• Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;372:1224-1229. PMID 33888596.
• Safety and metabolism-related outcomes of oral nicotinamide mononucleotide supplementation in adults: a systematic review and meta-analysis. Nutrients. 2026;18(14):2251. PMID 42514320.
• Long-term nicotinamide riboside use improves coordination and eye movements in ataxia telangiectasia. Mov Disord. 2024. PMID 37899683.
• NutraIngredients. Majority of NR dietary supplements tested by ChromaDex failing to meet label claims. 28 February 2025.