What are the key points in brief?
How well tolerated were NR and NMN in studies?
According to a 2026 systematic review, oral NR and NMN products were mostly well tolerated in human studies lasting weeks to months1.
In an eight-week randomized trial, adverse events under NR occurred no more often than under placebo. Skin flushing was not reported2.
What applies in pregnancy and breastfeeding?
EFSA assessed NR chloride as safe for healthy adults. It excluded pregnant and breastfeeding women from this statement. For them, it assessed only a lower daily amount as safe. The reason was a developmental study in rats. EFSA considered the safety margin from this study insufficient for this group3.
EFSA's 2026 safety assessment of NMN also applies to adults, excluding pregnant and breastfeeding women4.
What is known about high amounts and long-term effects?
EFSA points to experimental data. According to these, amounts of nicotinamide or its precursors far above requirements could have unwanted effects through several pathways. It considers further studies and possibly a reassessment of the upper limit for nicotinamide to be warranted6.
One review considers the usual use of nicotinamide to be safe. For long-term intake of high amounts, it sees possible risks of epigenetic changes, that is, changes in gene regulation7.
Which symptoms were reported with NAD+ infusions?
In a retrospective analysis, people reported moderate to severe gastrointestinal symptoms, a raised heart rate and chest pressure during NAD+ infusions. The symptoms subsided after the infusion5. More on this is on the page What is known about NAD+ IV infusions?.
What is known about cancer risk and interactions?
The human studies ran for weeks to months1. They can therefore hardly support statements about long-term cancer risk. The studies cited here also allow no reliable statements about interactions with medicines.
If you have or have had cancer, in pregnancy and breastfeeding, and if you take medicines regularly, a conversation with a doctor can bring clarity before any decision about NAD+ products. The five-step preparation helps you create a medication list for that conversation.
Which sources does this page rely on?
- Gallagher C, Emmanuel OO (2026). NAD⁺ supplementation for anti-aging and wellness: A PRISMA-guided systematic review of preclinical and clinical evidence. Ageing Research Reviews. DOI: 10.1016/j.arr.2026.103057
The review asks what studies on NAD+ products show for ageing and well-being. It systematically assesses 113 studies, 33 of them in humans. NR and NMN may raise NAD levels and appear well tolerated, while a clinical benefit remains open, and suitable trials of NAD+ infusions were lacking.
- Conze DB, Brenner C, Kruger CL (2019). Safety and Metabolism of Long-term Administration of […] (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults. Scientific Reports. DOI: 10.1038/s41598-019-46120-z
The trial examined how healthy adults with overweight tolerate nicotinamide riboside over eight weeks and how their blood values change. It was randomised, double-blind and placebo-controlled. Blood NAD+ may rise depending on the amount taken, and adverse events were about as frequent as with placebo.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) et al. (2019). Safety of nicotinamide riboside chloride as a novel food pursuant to Regulation (EU) 2015/2283 and bioavailability of nicotinamide from this source, in the context of Directive 2002/46/EC. EFSA Journal. DOI: 10.2903/j.efsa.2019.5775
The opinion assesses whether nicotinamide riboside chloride is safe as a novel food in food supplements. It is a scientific assessment by the European Food Safety Authority. EFSA considered it safe for healthy adults under the proposed conditions and, for pregnant and breastfeeding women, only in a smaller amount.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) et al. (2026). Safety of beta‐nicotinamide mononucleotide (β‐NMN) pursuant the regulation (EU) 2015/2283 and the bioavailability of nicotinamide from this source in the context of Directive 2002/46/EC. EFSA Journal. DOI: 10.2903/j.efsa.2026.10007
The opinion assesses whether synthetically produced β-NMN is safe as a novel food in food supplements. It is a scientific assessment by the European Food Safety Authority. EFSA considered it safe under the proposed conditions for adults, excluding pregnant and breastfeeding women.
- Reyna K et al. (2026). Intravenous infusion of nicotinamide adenine dinucleotide (NAD+) versus nicotinamide riboside (NR): a retrospective tolerability pilot study in a real-world setting. Frontiers in Aging. DOI: 10.3389/fragi.2026.1652582
The study compares how well NAD+ and NR infusions on four consecutive days are tolerated. It is a retrospective review of treatment records with 30 days of follow-up. NAD+ was more often linked to marked discomfort during the infusion and longer infusion times, and symptoms resolved once the infusion ended.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) et al. (2021). Extension of use of nicotinamide riboside chloride as a novel food pursuant to Regulation (EU) 2015/2283. EFSA Journal. DOI: 10.2903/j.efsa.2021.6843
The opinion examines whether nicotinamide riboside chloride can be used in further food categories. It is a scientific assessment by the European Food Safety Authority. EFSA found safety not established for meal replacements and drink mixes for the general population and considered use in certain special foods for adults safe.
- Hwang ES, Song SB (2020). Possible Adverse Effects of High-Dose Nicotinamide: Mechanisms and Safety Assessment. Biomolecules. DOI: 10.3390/biom10050687
The review asks which adverse effects high-dose nicotinamide might have. It is a review of mechanisms and safety. The authors consider current usual use safe but see possible risks of epigenetic changes with long-term high-dose intake.