Can NAD+ Infusions Resolve Persistent Fatigue in Long COVID Patients?
What NAD+ Infusions Are
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every living cell. It shuttles electrons in mitochondrial respiration, which is how cells make ATP. Infusions deliver NAD+ directly into the bloodstream, bypassing the gut. Clinics offer them for fatigue, brain fog, and recovery support. The idea is simple: if cells are starved for NAD+, supplying it might restore energy metabolism.
Long COVID fatigue is not ordinary tiredness. It is a post-exertional malaise that can last days after minor activity. Some researchers suspect mitochondrial dysfunction plays a role. NAD+ sits at the center of that pathway. So the question becomes whether raising NAD+ levels can shift the biology enough to matter.
There are other peptides and bioregulators sometimes mentioned alongside NAD+ for Long COVID. GHK-Cu is a copper-binding peptide studied for tissue repair and inflammation. Epitalon, Vesugen, Cortagen, and Thymalin are short peptides from Russian research, each with different proposed targets. None of them are approved for Long COVID. But they appear in discussions because they intersect with aging, immune, and vascular pathways that Long COVID disrupts.
Mechanism: Why NAD+ Might Matter in Long COVID
NAD+ has two main jobs relevant here. First, it accepts electrons in glycolysis and the Krebs cycle, becoming NADH. NADH then donates electrons to the electron transport chain. Without enough NAD+, that chain slows. ATP output drops. Cells feel tired.
Second, NAD+ is a substrate for enzymes called sirtuins and PARPs. Sirtuins regulate mitochondrial biogenesis and stress resistance. PARPs repair DNA damage. When PARPs are overactive, they can deplete NAD+ stores. Some Long COVID studies report markers of oxidative stress and DNA damage. That could drain NAD+ and leave less for energy production.
There is also a vascular angle. Endothelial dysfunction is common in Long COVID. NAD+ influences nitric oxide bioavailability through sirtuin pathways. Poor blood flow means less oxygen delivery to tissues. That can feel like fatigue even when mitochondrial function is normal. GHK-Cu and Vesugen have been studied for vascular repair in other contexts, which is why they sometimes appear in Long COVID discussions. But the evidence for NAD+ itself is more direct.
Research Summary: What the Data Show
Human trials of NAD+ infusions for Long COVID are almost nonexistent. Most evidence comes from small pilot studies, case reports, and extrapolation from chronic fatigue syndrome (ME/CFS) research. ME/CFS shares many features with Long COVID, including post-exertional malaise and mitochondrial abnormalities.
One small open-label study gave NAD+ infusions to 9 patients with ME/CFS. Fatigue scores improved in most, but the study had no control group. Another case series reported benefit in 3 Long COVID patients. Those are anecdotes, not proof. A 2023 review of NAD+ metabolism in Long COVID concluded that NAD+ depletion is plausible but unproven as a therapeutic target.
Preclinical work is stronger. Animal models of chronic fatigue show that NAD+ precursors like nicotinamide riboside improve mitochondrial function and endurance. But infusion of NAD+ itself is different from oral precursors. NAD+ is a large, charged molecule. It does not easily cross cell membranes. Some researchers argue that infusions mainly raise extracellular NAD+, which is then broken down into precursors that cells can take up. That is a slower, indirect route.
There is also a question of dose and frequency. Infusions are typically given over several hours, sometimes multiple times per week. The half-life of NAD+ in blood is short. Sustained benefit would require repeated administration or a shift in cellular metabolism that persists. No published trial has tested this rigorously in Long COVID.
Other peptides have even less evidence. Thymalin and Cortagen have been studied in Russian trials for immune and cognitive function, mostly in older adults. GHK-Cu and Thymalin have been proposed for immune rejuvenation, but Long COVID is not a simple immune deficiency. It involves autoantibodies, viral persistence, and microclots. A single peptide is unlikely to address all of that.
Practical Considerations for Clinics and Patients
NAD+ infusions are not cheap. A single session can cost several hundred dollars. A course of 5 to 10 infusions is often recommended, though that recommendation is not based on trial data. Insurance rarely covers it for Long COVID. Patients should ask about the exact formulation, dose, and duration of infusion. Some clinics add other compounds like vitamin C or glutathione. Those additions have their own evidence gaps.
Side effects are usually mild: flushing, nausea, headache, or discomfort at the infusion site. Some patients report a transient feeling of warmth or chest tightness. These are not well quantified in the literature. Serious adverse events appear rare, but reporting is sparse. Anyone considering an infusion should have baseline labs, especially liver enzymes and kidney function, because NAD+ metabolism involves both organs.
There is also a drug interaction concern. NAD+ can lower blood pressure in some people. Patients on antihypertensives should be monitored. Those with a history of mast cell activation, which is common in Long COVID, may react to the infusion itself. Starting with a low dose and slow rate is common practice, though not standardized.
For researchers, the key variables are dose (typically 250 to 1000 mg per infusion), frequency (weekly to several times per week), and duration (4 to 12 weeks). None of these have been optimized in controlled trials. The route matters too. Intravenous NAD+ bypasses first-pass metabolism, but oral precursors like nicotinamide riboside or NMN are cheaper and easier to take daily. NAD+ nasal sprays have been studied for skin and metabolic effects, but their bioavailability for systemic fatigue is unclear.
Open Questions
The biggest unknown is whether raising NAD+ levels in blood translates to higher NAD+ inside mitochondria in relevant tissues like muscle and brain. Infusions may simply be an expensive way to deliver precursors that oral supplements could provide. No head-to-head trial exists.
Another open question is timing. Long COVID is not a single disease. Some patients have persistent viral RNA, others have autoimmunity, others have microclots. NAD+ might help only the subset with mitochondrial dysfunction. Biomarkers like lactate, CoQ10, or muscle biopsy findings could identify responders. That has not been tested.
Finally, there is the question of whether NAD+ infusions are better than exercise or pacing. Exercise is often harmful in Long COVID because of post-exertional malaise. Pacing helps but does not cure. NAD+ is sometimes marketed as a way to "restore energy" without exertion. That is an appealing claim, but it has not been validated in a randomized trial.
Side-effect and adverse-event data for many peptides is sparse. Absence of reported harm does not equate to absence of risk.