NAD+ Side Effects: What Human Studies and FDA Show

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In the one clinic study that reported side effects from IV NAD+, all 6 clients had abdominal cramping, nausea, vomiting, a faster heart rate and chest pressure during the infusion, and the authors wrote that these ceased when it ended. A smaller 2019 pilot saw none. The evidence is two small studies, and almost nothing is published on the injections and nasal sprays sold for home use.

I’m Judy, I’m not a medical professional, and this page is built from published studies and FDA pages rather than personal results. Every claim below comes from the sources listed at the bottom, and where the evidence is small I say so in the sentence.

Table of Contents

What Are the Most Common NAD+ Side Effects?

It depends on how NAD+ is given, and the best-documented side effects belong to IV infusion. In a 2026 study in Frontiers in Aging, all 6 clients who received 500 mg of IV NAD+ reported moderate to severe abdominal cramping, diarrhea, nausea, vomiting, a faster heart rate, throat pain, congestion and chest pressure during infusions. The authors wrote that these experiences ceased immediately when the infusion was completed.

For oral NAD-family supplements, a 2024 systematic review of 10 randomized trials with 489 participants reported that every study showed some side effects, most commonly muscle pain, nervous disorders, fatigue, sleep disturbance and headaches, and that none of the cataloged events posed a serious health risk. That review’s conclusions focus on oral NADH and precursors, not injected NAD+, so it does not tell you what a shot or an IV will feel like.

What Side Effects Did Human Studies Report for IV NAD+?

The 2026 clinic study: 6 clients, 4 days in a row

This is the closest thing to a real-world report. Researchers reviewed records from a commercial wellness clinic where clients received four consecutive days of 500 mg IV NAD+ (6 clients) or IV nicotinamide riboside (8 clients), with 30 days of follow-up, according to the study abstract. Clients controlled their own infusion rate based on tolerance, and the NAD+ group’s total infusion time averaged 97 minutes versus 37 minutes for the nicotinamide riboside group, because moderate to severe symptoms slowed the drip.

The same paper reported no significant changes in the liver enzymes ALT and AST, the inflammation marker hsCRP, BUN/creatinine or TSH. Alkaline phosphatase fell in the NAD+ group but stayed within normal reference ranges. Read it with its limits in mind: it was retrospective, tiny, had no placebo group, and was funded by the clinic company whose employees wrote it.

The 2019 pilot: 11 healthy men, a 6 hour infusion

An earlier pilot study in Frontiers in Aging Neuroscience gave 750 mg of NAD+ intravenously over 6 hours to 8 healthy men aged 30 to 55, with 3 more men receiving saline. The paper states that no adverse events were observed during the infusion in either group, and the liver markers GGT, LD and AST were lower at 8 hours in the NAD+ group while bilirubin was higher. Eleven men is a very small sample, and no women were included.

The two results do not contradict each other as much as they look. The infusions ran at very different speeds, in different people, in different settings, so neither one settles how common these symptoms are.

Why Does NAD+ Infusion Cause Cramping, Nausea and Chest Pressure?

Nobody has proven the cause. The authors of the 2026 clinic study wrote that nausea, malaise, sweating, stomach cramping and headache with NAD+ may be related to the proinflammatory environment created by raising extracellular NAD+ to very high concentrations, and that anecdotal reports say slow, prolonged infusions are used to minimize the discomfort. That is a hypothesis in the paper’s introduction, not a finding of the study.

What Has FDA Said About NAD+ Injection Side Effects?

FDA’s page on ingredients suitable for sterile compounding (content current as of October 30, 2024, which I read on October 19, 2026) says the agency is aware of compounders using food-grade NAD+ sold by repackagers to make intravenous products. FDA says food-grade ingredients are not suitable for sterile drugs without appropriate processing because of the high risk of microbial and endotoxin contamination.

The same page says FDA has received adverse event reports after use of NAD+ injectable drugs, including severe chills, shaking, vomiting and fatigue, with some requiring medical treatment, and that these reactions are consistent with excessive levels of endotoxins. The agency encourages patients and clinicians to report adverse events. In practice that means the product’s source and sterility matter, not only the dose.

What Side Effects Do Oral NAD+ Supplements Cause?

The 2024 review above is the main source. Its side effects (muscle pain, nervous disorders, fatigue, sleep disturbance, headaches) came from oral NADH and precursor trials in people with conditions such as chronic fatigue syndrome, Parkinson’s disease and prediabetes, so they are not a clean guide for a healthy adult taking an NAD+ capsule. The 2026 Ageing Research Reviews systematic review adds that oral nicotinamide riboside and NMN were generally well tolerated over weeks to months in humans, while effects on health outcomes were mixed and often null. For adverse events in NMN trials specifically, see my page on NMN side effects.

What Do We Know About Subcutaneous NAD+ Injections and Nasal Sprays?

None of the human studies cited on this page tested at-home subcutaneous injections or nasal spray NAD+, so there are no trial numbers for them here. The 2026 Ageing Research Reviews analysis, which covered studies through October 2025, found no eligible outcomes trials of intravenous or intramuscular NAD+ itself for anti-aging or wellness, and treated one IV NAD+ pharmacokinetic pilot as context only. Whether a smaller, slower dose feels milder is plausible, and it is not something I can show you from a study. For what people hope injections do, see my guide to NAD+ injection benefits.

Is NAD+ Safe for the Liver, Heart and Cancer History?

The studies above looked at liver enzymes over days to a month and did not report a harmful rise, but they were small and short. The 2026 clinic study reported a faster heart rate and chest pressure during NAD+ infusions, which is a reason to tell the person running an infusion right away rather than push through it.

On cancer, a 2020 review in Biochemical Society Transactions notes that many cancers have an increased dependency on NAD+. That is laboratory-level biology, and none of the human studies here tested whether NAD+ injections affect cancer risk. It is still a reason a clinician should hear your history: the clinic in the 2026 study listed pregnancy and a family or recent history of cancer as contraindications to its IV therapy.

Is NAD+ Compounding Regulated by FDA?

FDA’s list of bulk drug substances nominated for compounding under section 503A (updated May 14, 2026, read October 19, 2026) places nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide disodium reduced (NADH) in category 1, “Bulk Drug Substances Under Evaluation.” It places beta-nicotinamide adenine dinucleotide disodium salt trihydrate in category 3, “Nominated Without Adequate Support.” Neither appears in category 2, the list of substances that raise significant safety risks. Category 1 means FDA is still evaluating them. It is not an endorsement.

What a Telehealth NAD+ Page Says Compared With the Studies

If you decide to explore NAD+ through telehealth, a licensed clinician should decide whether it is right for you, not a product page. Shed’s NAD+ page, which I read on October 19, 2026, describes monthly subscriptions for an NAD+ nasal spray and for NAD+ injections. It says you complete an online medical questionnaire, a licensed provider reviews your information, and if approved, medication is shipped to you. See Shed’s NAD+ page here.

On safety, the same page says supplementation is generally well tolerated and that some people may experience mild flushing, headaches or nausea, especially at higher doses. That description is milder than the IV study results above, which tested a different route, so ask any provider what side effects they have seen with their exact product, where it is compounded, and how it is tested. Shed’s page also lists benefits such as slowed aging and boosted energy, and the research I cite does not establish those for injections.

When to Talk to a Clinician About NAD+ Side Effects

I’m not a doctor, and this page is not medical advice. If you take medication, are pregnant or breastfeeding, have heart, liver or cancer history, or feel chest pressure, a racing heart or trouble breathing during any infusion, tell your prescriber or the clinician running the infusion, and seek emergency care if symptoms are severe. Bring the studies listed below to your appointment. To compare NAD+ with its precursor, read NAD+ vs NMN, and for what telehealth programs charge, see how much NAD+ therapy costs.

Frequently Asked Questions

Do NAD+ side effects go away on their own?

In the 2026 clinic study of IV NAD+, the symptoms ended immediately once the infusion was completed. That study followed 6 NAD+ clients, so it cannot tell you how long reactions last after other routes or products.

Is IV NAD+ safe?

A 2019 pilot gave 750 mg over 6 hours to 8 healthy men and saw no adverse events, while a 2026 clinic study found moderate to severe symptoms in all 6 clients infused with 500 mg. Safety depends on the product, the infusion speed and the person, and FDA has received reports of severe chills, shaking and vomiting after NAD+ injectables.

Can NAD+ damage your liver?

Neither small infusion study reported a harmful rise in liver enzymes, but they followed people for hours to 30 days. Long-term liver safety of repeated NAD+ injections has not been studied in the sources I cite.

Do NAD+ nasal sprays have fewer side effects than injections?

No study cited here compared them. A telehealth company says mild flushing, headache or nausea can occur, especially at higher doses, but that is the seller’s statement and not trial data.

Who should avoid NAD+ therapy?

Ask your clinician. The clinic in the 2026 study excluded clients who were pregnant or had a family or recent history of cancer, so those are reasons to raise before any infusion.

What does FDA say about chills and vomiting after NAD+ injectables?

FDA says reports of severe chills, shaking, vomiting and fatigue are consistent with excessive endotoxin levels, which it links to contaminated, non-sterile-grade ingredients. It has not said that explains every report. Ask where a product is compounded and how it is tested.

Sources

NAD+ Side Effects: What Human Studies and FDA Reports Show