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NAD Precursors Titration & Tapering Algorithms: A Clinical Prescriber's Guide

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At a glance

  • Compounds / NMN and NR, oral NAD+ precursors
  • Regulatory status / Dietary supplements, not FDA-approved drugs [6]
  • NMN doses tested / 250 mg/day to 1,250 mg once daily [1][2][3]
  • NR doses tested / 1 g/day to 1,500 mg twice daily [7][4][5]
  • Injectable NAD+ / Compounded product, not FDA-approved [8]
  • Human drug-interaction studies / None identified in a 2023 review [9]

What doses were tested?

NMN was given as 250 mg once daily for 12 weeks (30 healthy adults, NMN or placebo) [1], 300, 600 or 900 mg once daily for 60 days (80 middle-aged adults randomized across the three doses and placebo) [2], and 1,250 mg once daily for up to 4 weeks (31 healthy adults, NMN or placebo) [3]. NR was given as 1 g/day for 21 days (12 men aged 70 to 80, crossover) [7], 1,000 mg twice daily for 12 weeks (40 men with obesity, NR or placebo) [4], and 1,500 mg twice daily for 4 weeks (20 people with Parkinson's disease, 10 on NR) [5].

What side effects were reported?

NMN 1,250 mg once daily for up to 4 weeks caused no severe adverse events and no changes beyond normal physiological variation [3]. At 250 mg/day for 12 weeks there were no laboratory abnormalities and no obvious adverse effects [1], and 300 to 900 mg/day for 60 days raised no safety issues [2]. NR was well tolerated in a six-week crossover trial [10]; 1,000 mg twice daily for 12 weeks produced no serious adverse events in the 40-man trial [4], and 3,000 mg/day for 4 weeks produced no moderate or severe adverse events in the 20-person Parkinson's disease trial [5].

What happens when someone stops?

The trial results cited here describe outcomes during dosing. Safety data beyond about 12 weeks are lacking, and the trials were generally small with widely varying doses and durations [9].

Does a higher blood NAD+ level mean more benefit?

Blood NAD+ rises in these trials, but that has not reliably translated into function. In the 80-adult NMN dose-ranging trial, blood NAD was highest at 600 and 900 mg/day [2]. In 12 men aged 70 to 80, 21 days of NR did not raise muscle NAD+, although a marker of NAD+ synthesis doubled, and mitochondrial respiration was unchanged [7]. A 2025 meta-analysis of randomized trials in older adults found NMN had no significant effect on muscle index, grip strength, gait speed or the 5-times chair stand [11].

What is the regulatory status?

NMN and NR are sold in the US as oral dietary supplements and neither is an FDA-approved drug [6]. FDA's response to the citizen petition in docket FDA-2023-P-0872, dated 2025-09-29, concluded that NMN is not excluded from the supplement definition [6][12]. FDA's 2016 letter on GRAS notice GRN 000635 for nicotinamide riboside chloride raised no questions and stated that FDA had not made its own GRAS determination [13]. Injectable or IV NAD+ is a compounded product, not an FDA-approved drug [8]. A 2023 review identified no human drug-interaction studies of NMN or NR [9].

Frequently asked questions

Do NMN or NR need to be titrated?
No titration schedule exists. The trials gave NMN 250 mg/day for 12 weeks or NR 1,000 mg twice daily for 12 weeks [1][4].
Do NMN or NR need to be tapered when stopped?
No taper schedule exists, and safety beyond about 12 weeks is not established [9].
Are NMN and NR FDA-approved?
No. Both are sold as dietary supplements and neither is FDA-approved [6]. Injectable or IV NAD+ is a compounded product, not an FDA-approved drug [8].
Do NMN or NR interact with prescription drugs?
A 2023 review identified no human drug-interaction studies of NMN or NR, including CYP, transporter or pharmacodynamic studies [9].

References

  1. Okabe K, Yaku K, Uchida Y, Fukamizu Y, Sato T, Sakurai T, et al. Oral Administration of Nicotinamide Mononucleotide Is Safe and Efficiently Increases Blood Nicotinamide Adenine Dinucleotide Levels in Healthy Subjects. Front Nutr. 2022;9:868640. Oral Administration of Nicotinamide Mononucleotide Is Safe and Efficiently Increases Blood Nicotinamide Adenine Dinucleotide Levels in Healthy Subjects
  2. Yi L, Maier AB, Tao R, Lin Z, Vaidya A, Pendse S, et al. The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial. Geroscience. 2023;45(1):29-43. The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial
  3. Fukamizu Y, Uchida Y, Shigekawa A, Sato T, Kosaka H, Sakurai T. Safety evaluation of β-nicotinamide mononucleotide oral administration in healthy adult men and women. Sci Rep. 2022;12(1):14442. Safety evaluation of β-nicotinamide mononucleotide oral administration in healthy adult men and women
  4. Dollerup OL, Christensen B, Svart M, Schmidt MS, Sulek K, Ringgaard S, et al. A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects. Am J Clin Nutr. 2018;108(2):343-353. A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects
  5. Berven H, Kverneng S, Sheard E, Søgnen M, Af Geijerstam SA, Haugarvoll K, et al. NR-SAFE: a randomized, double-blind safety trial of high dose nicotinamide riboside in Parkinson's disease. Nat Commun. 2023;14(1):7793. NR-SAFE: a randomized, double-blind safety trial of high dose nicotinamide riboside in Parkinson's disease
  6. Official web page. Official web page
  7. Elhassan YS, Kluckova K, Fletcher RS, Schmidt MS, Garten A, Doig CL, et al. Nicotinamide Riboside Augments the Aged Human Skeletal Muscle NAD+ Metabolome and Induces Transcriptomic and Anti-inflammatory Signatures. Cell Rep. 2019;28(7):1717-1728.e6. Nicotinamide Riboside Augments the Aged Human Skeletal Muscle NAD+ Metabolome and Induces Transcriptomic and Anti-inflammatory Signatures
  8. Bulk Drug Substances Used in Compounding of the FD&C Act | FDA. Bulk Drug Substances Used in Compounding of the FD&C Act | FDA
  9. Freeberg KA, Udovich CC, Martens CR, Seals DR, Craighead DH. Dietary Supplementation With NAD+-Boosting Compounds in Humans: Current Knowledge and Future Directions. J Gerontol A Biol Sci Med Sci. 2023;78(12):2435-2448. Dietary Supplementation With NAD+-Boosting Compounds in Humans: Current Knowledge and Future Directions
  10. Martens CR, Denman BA, Mazzo MR, Armstrong ML, Reisdorph N, McQueen MB, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9(1):1286. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults
  11. Prokopidis K, Moriarty F, Bahat G, McLean J, Church DD, Patel HP. The Effect of Nicotinamide Mononucleotide and Riboside on Skeletal Muscle Mass and Function: A Systematic Review and Meta-Analysis. J Cachexia Sarcopenia Muscle. 2025;16(3):e13799. The Effect of Nicotinamide Mononucleotide and Riboside on Skeletal Muscle Mass and Function: A Systematic Review and Meta-Analysis
  12. Official web page. Official web page
  13. Agency Response Letter GRAS Notice No. GRN 000635 | FDA. Agency Response Letter GRAS Notice No. GRN 000635 | FDA
Evidence overview for classes nad precursors: NAD Precursors Titration & Tapering Algorithms: A Clinical Prescriber's Guide