NAD+ Therapy: Injections vs Capsules vs IV

NAD+ therapy aims to raise levels of nicotinamide adenine dinucleotide, a coenzyme every cell needs for energy production and DNA repair, which declines with age. It can be delivered as oral precursors (NMN or NR capsules), as injections, or as IV infusions. Oral precursors have the most controlled human data and reliably raise blood NAD+; IV and injectable forms are faster and more expensive but have little controlled evidence of clinical benefit. None has been shown to slow human aging.

What Is NAD+ and Why Does It Matter?

NAD+ is a coenzyme found in every living cell. It plays three major roles:

• Energy metabolism. It shuttles electrons in the mitochondria so cells can produce ATP.
• DNA repair. It is the fuel for PARP enzymes that repair damaged DNA.
• Sirtuin activity. Sirtuins are enzymes involved in metabolic regulation and stress resistance, and they require NAD+ to function.

Tissue NAD+ levels decline with age in animal models and in some human tissues. In mice, restoring NAD+ improves several markers of metabolic and mitochondrial health. That is the rationale for NAD+ therapy. The open question is how much of this translates to meaningful benefits in people. For background on why mitochondria matter, see The Role of Mitochondrial Health in Aging.

NAD+ Therapy Options Compared

Oral precursors: NMN and NR

NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are building blocks the body converts into NAD+. Multiple 8–12-week randomized trials show they raise blood NAD+ levels and are well tolerated in the short term.

Clinical outcomes have been mixed. One frequently cited 2021 study in Science found that 10 weeks of NMN improved muscle insulin sensitivity in a small group of postmenopausal women with prediabetes. Other trials have shown small or no improvements in walking speed, grip strength or endurance. My summary: oral precursors reliably change a biomarker, while their effect on how people feel and function is modest and inconsistent.

Injectable NAD+

Subcutaneous or intramuscular NAD+ has become popular as a middle ground between capsules and IV. The appeal is bypassing digestion. However, there are very few published studies of injectable NAD+, and injection can be uncomfortable. There is also a deeper scientific question: NAD+ is a large, charged molecule, and much extracellular NAD+ appears to be broken down into smaller precursors before entering cells — meaning the body may process injected NAD+ similarly to oral precursors.

IV NAD+ infusions

IV infusions deliver large amounts directly into the bloodstream. Patients often report feeling energized, but IV NAD+ has not been tested in large controlled trials for fatigue, cognition or aging. Infusions frequently cause flushing, nausea, abdominal cramping or chest tightness if given too quickly, which is why they are often run slowly over hours. They also carry the usual risks of IV access and the highest cost.

Safety Considerations

NAD+ precursors are generally well tolerated in short-term studies, but several cautions apply:

• Long-term data are lacking. We do not have multi-year safety or outcome studies.
• Cancer (theoretical). NAD+ supports cell growth and repair in all cells, including cancer cells. In anyone with an active malignancy, I avoid NAD+-boosting therapy pending better data.
• Methylation. Breaking down excess nicotinamide uses methyl groups; with long-term use, checking homocysteine, B12 and folate is reasonable.
• Pregnancy and breastfeeding. No safety data.
• Quality. Supplements vary in purity and content, and compounded IV products depend on the pharmacy's standards.

Regulatory Status

NMN has had an unusual regulatory history. In 2022, FDA took the position that NMN could not be sold as a dietary supplement. On September 29, 2025, FDA reversed that position after citizen petitions, finding NMN is not excluded from the supplement definition. NMN and NR remain supplements, not FDA-approved drugs. IV and injectable NAD+ are not FDA-approved for energy, cognition or anti-aging uses.

The Foundation Comes First

Exercise is one of the strongest natural stimuli for NAD+ metabolism and mitochondrial health. Consistent aerobic training — including the type described in Zone 2 Cardio: The Longevity Exercise Protocol — sleep, avoiding excess alcohol, and metabolic health all support the same pathways that NAD+ products target. In my experience, patients who add a precursor to a solid foundation are more likely to notice a difference than those hoping a supplement can replace one. For help separating useful supplements from marketing, see Supplements Worth Taking vs Marketing Hype.

How We Approach NAD+ Therapy at Laeeq M.D.

At Laeeq M.D., NAD+ discussions begin with the reason behind the request. Fatigue, brain fog and low exercise tolerance have many treatable medical causes — thyroid disease, anemia, sleep apnea, depression, medication effects — that should be ruled out first. If an NAD+ approach still makes sense, we choose the form based on evidence, cost and your preferences, with any dosing individualized after evaluation and labs.

Sources

• Anti-aging compound that improves metabolic health in mice improves muscle glucose metabolism in people — Washington University School of Medicine (on Yoshino et al., Science), 2021
• FDA Declares Nicotinamide Mononucleotide Is a Dietary Supplement — Venable LLP, 2025

Book a Consultation

If you are considering NAD+ therapy, a physician review can help you decide whether it fits your goals — and whether something else explains your symptoms. Dr. Laeeq offers 60-minute consultations, virtually or in person in Reston, VA. Book a consultation to build an evidence-based plan.

This article is for educational purposes and is not medical advice. Discuss any treatment with a licensed physician who knows your history.