The honest answer is that almost nobody has measured this. People who sit through NAD⁺ infusions consistently describe chest pressure, nausea and cramping, and that is now documented in one published chart review — but for NAD⁺ given by injection into muscle or under the skin, which is what most telehealth providers ship, there is no published human study of any design reporting what happens.
That is a different statement from “it is dangerous”, and it is also a different statement from “it is well tolerated.” It means the row is blank. Below is the one study that recorded symptoms, the census showing what else exists, and what the blank actually costs you. If you want the comparison across all three routes instead, side effects by format covers that, and the products themselves sit on the injection board and the IV board.
The one study that recorded what people felt
A 2026 retrospective review of electronic medical records at a commercial infusion clinic compared intravenous NAD⁺ against intravenous nicotinamide riboside. Clients received four consecutive days of 500 mg by either route, with 30 days of follow-up. The tolerability split cleanly, and not in the direction the NAD⁺ price tag implies.
Participants receiving NAD⁺ intravenously reported moderate to severe gastrointestinal symptoms, increased heart rate, and chest pressure during the infusions. Participants receiving NR intravenously reported minor tongue, jaw and arm tingling and mild cramping. All symptoms resolved when the infusion finished. Because the NAD⁺ symptoms were more severe, the drip had to be slowed: infusions averaged 97 minutes for NAD⁺ against 37 minutes for NR. Liver enzymes, hsCRP, kidney function and TSH did not change significantly in either group [1].
That is a retrospective chart review, not a randomized trial — no blinding, no control group, no prespecified symptom instrument, and a self-selected commercial clientele. Take it as the best available description of what the drip feels like, and as confirmation that the infusion-rate ritual clinics perform has a reason behind it. Do not take it as a safety clearance; it was not designed to be one.
What we searched, and when
An absence claim is only worth anything with its searching attached, so here is ours. In September 2026 we queried PubMed for randomized controlled trials of nicotinamide adenine dinucleotide administered subcutaneously or intramuscularly. The search returned a single record, and it is not an injection study at all — it is a telehealth exercise pilot in childhood cancer survivors using oral nicotinamide riboside [2]. Run alongside it as a known-good control, the same query shape for injected testosterone returned more than two hundred randomized trials, so the instrument was working and the database was reachable.
You do not have to take our search for it, which is the better position to be in. A PRISMA-guided systematic review published in 2026 swept human and rodent intervention studies of NAD-related compounds from January 2010 to October 2025, identified 113 eligible studies including 33 human intervention studies of which 28 were randomized, and stated plainly that no eligible outcomes trial evaluated intravenous or intramuscular NAD⁺ itself for anti-aging or wellness indications [3]. That is a published census by people with no stake in our argument.
The trial that does exist, and why it is not about you
There is one randomized, placebo-controlled trial of intravenous NAD⁺. It enrolled 180 adults with heart failure from ischemic cardiomyopathy and gave 10 mg a day for seven days alongside guideline-directed medical therapy, reporting a greater one-month gain in ejection fraction than placebo (45.44 ± 8.55% vs 42.44 ± 9.09%, p = 0.024) [4].
Ten milligrams a day, in monitored cardiac patients, in hospital. A single wellness infusion typically sells 250 mg or more, and the milligram figures providers publish run to 1,000 mg a month. Whatever that trial establishes, it does not establish a side-effect profile for a dose twenty-five times larger given to healthy people for a reason the trial never studied.
The other relevant human study is a pharmacokinetic pilot that infused NAD⁺ at 3 µmol per minute over six hours and found no change in plasma NAD⁺ or its metabolites until after two hours, concluding the infused molecule was being rapidly and completely cleared from plasma for at least that long [5]. It tracked where the molecule went. It did not ask anyone how they felt.
What a blank row actually costs you
Three specific things, none of which a seller has an incentive to name.
You cannot be warned about what has not been catalogued. With an approved drug, the label lists adverse events by frequency because a sponsor was required to count them. Nothing here counted them, so the consent conversation is being improvised from practice experience.
Interactions are unexamined rather than cleared. No study has tested injected NAD⁺ against the medications you take. Silence is not a negative result.
The preparation itself is unreviewed. Injectable and IV NAD⁺ are compounded, which means they are not FDA-approved and the FDA has not reviewed them for safety, efficacy or quality before they are dispensed. Sterility, purity and dose accuracy rest on the pharmacy, and what the regulatory labels actually mean is worth reading before a first purchase.
If you are going ahead anyway
Ask the milligram figure, the concentration and whether it is per injection, per vial or per month — three different units that look identical on a checkout page. Ask what the clinic does when someone reports chest pressure, because the published answer is to slow the rate. Give your prescriber the full medication list. And treat route and technique as their decision rather than a search result.
Then price the missing evidence in. The format with an actual adverse-event ledger is the cheap one: oral precursors have randomized safety trials with placebo arms, and they cost a fraction of a drip. In this category the evidence ranking and the price ranking run in opposite directions, which is the single most useful thing to know before you book.