These three get sold together on the same menu, which implies they sit on the same evidence. They do not. B12 is a well-established treatment when you are actually deficient. NAD+ and glutathione are biologically interesting and considerably better supported in theory than in human outcome data. Knowing which is which lets you spend on the first and make an informed choice about the others.
B12: the one with the strongest case
Vitamin B12 is required for red blood cell formation, nerve function and DNA synthesis. Deficiency causes fatigue, pins and needles, balance problems, memory changes, sore tongue and anemia, and if left long enough, some of the neurological damage does not fully reverse.
Injections are genuinely indicated when absorption is the problem rather than intake, which is a real and common situation:
- Pernicious anemia, an autoimmune condition preventing B12 absorption
- After bariatric surgery or bowel resection
- Crohn’s disease and other malabsorption
- Long-term metformin use, which lowers B12 over time
- Long-term acid-suppressing medication
- Strict vegan diets without supplementation
- Older adults, in whom stomach acid production often falls
The honest caveat: if your B12 is normal and you are not deficient, an injection is very unlikely to give you energy. The “B12 shot for a boost” sold to people with normal levels is the part of this that is marketing rather than medicine. Test first. It is an inexpensive blood test, and it turns a guess into a treatment.
NAD+: real biology, thin human evidence
NAD+ is a coenzyme every cell uses for energy production and DNA repair, and levels do decline with age. That is genuine biology, and the research interest in it is legitimate.
What has not been established is that giving it by IV or injection produces the benefits it is marketed for: energy, mental clarity, slowed aging, addiction recovery. Most supporting data is preclinical or from small studies. Oral precursors such as NR and NMN reliably raise NAD levels in humans, but raising a level is not the same as producing a clinical benefit, and the outcome trials are not there yet.
It is also worth knowing that IV NAD+ is not FDA approved for any condition, and that infusions commonly cause flushing, chest tightness, nausea and cramping, which is why they are run slowly.
None of this makes it worthless. It makes it experimental, and the honest framing is that you are trying something plausible with incomplete evidence, at your own cost, rather than receiving an established treatment.
Glutathione: the same shape of answer
Glutathione is the body’s principal intracellular antioxidant and is central to how the liver handles toxins. Depletion is documented in various disease states.
Whether supplementing it intravenously improves health in people who are not ill is not established. It has been studied in Parkinson’s disease with mixed and largely unconvincing results. Absorption of oral glutathione is poor, which is the usual argument for IV, but a better delivery route for an unproven benefit is still an unproven benefit.
One thing that does deserve a clear warning: glutathione is widely marketed for skin lightening. That use is not approved, the doses used are often high, and regulators have flagged safety concerns about injectable products sold for it. That is not a wellness treatment.
IV or intramuscular?
IM injection is quick, cheaper and adequate for most vitamin repletion, including B12. IV delivers a larger volume and bypasses absorption entirely, which matters for some agents and is mostly a delivery preference for others. IV is not automatically superior, and framing it that way is a sales technique rather than a clinical one.
How we approach it
The rule here is simple: test, then treat. If you are deficient in something, correcting it can make a real difference, and we would rather find that on a blood panel than guess at it with a menu.
Where the evidence is thin, we will say so. Some patients still choose to try NAD+ or glutathione, and that is a reasonable adult decision when it is made with accurate information rather than a promise of a transformation the data does not support.
Wellness and vitamin injections sit alongside the rest of what we do rather than replacing it. If fatigue is the reason you are considering these, it deserves a proper workup first: thyroid problems vs. “adrenal fatigue” covers what that actually looks like.
Consults are available in person at our Deerfield Beach clinic and by telehealth anywhere in Florida.
Medically reviewed by Krishna Borges, MSN, APRN, FNP-C. This article is for general education and is not a substitute for individual medical advice.