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NMN and NR Drug Interactions: A Complete Clinical Profile

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At a glance

  • NAD+ precursor class / Both NMN and NR convert to NAD+ via distinct but converging enzymatic steps
  • Typical oral dose / 250 mg to 1,000 mg once daily for NMN; 300 mg to 1,000 mg for NR
  • FDA status / NMN removed from dietary supplement definition (Nov 2022); NR sold as supplement (GRAS since 2016)
  • Primary metabolism / NMN is converted by NMNAT enzymes; NR is phosphorylated by NR kinases (NRK1/2) to NMN, then to NAD+
  • Known human trial safety / Yoshino et al. (Science 2021, N=25) reported no serious adverse events at 250 mg/day NMN over 10 weeks
  • Key interaction pathway / NAD+-dependent enzymes (SIRT1-7, PARP1/2, CD38) modulate drug metabolism and DNA repair
  • Highest-concern drug classes / Alkylating chemotherapies, PARP inhibitors, anticoagulants, insulin/sulfonylureas
  • Pharmacokinetic interactions / Limited CYP450 involvement; primary concern is pharmacodynamic, not pharmacokinetic
  • Monitoring recommendation / Fasting glucose and INR checks when co-administered with antidiabetics or anticoagulants

How NMN and NR Raise NAD+ and Why That Creates Interaction Risk

NMN and NR are both precursors to nicotinamide adenine dinucleotide (NAD+), a coenzyme active in over 500 enzymatic reactions. NR enters cells via equilibrative nucleoside transporters and is phosphorylated by NR kinases (NRK1 and NRK2) to form NMN. NMN itself is converted to NAD+ by nicotinamide mononucleotide adenylyltransferases (NMNAT1-3) in the nucleus, cytoplasm, and mitochondria 1.

The interaction risk does not come from conventional cytochrome P450 competition. Neither NMN nor NR is a meaningful CYP substrate or inhibitor based on available preclinical data. Instead, the concern is pharmacodynamic: raising NAD+ amplifies the activity of sirtuins (SIRT1-7), poly(ADP-ribose) polymerases (PARP1/2), and the NADase CD38. Each of these enzyme families intersects directly with the mechanism of action of specific drug classes.

The interaction profile that follows is built from mechanistic pharmacology, animal co-administration studies, and case-report-level human evidence. Prescribers should treat these interactions as plausible but incompletely quantified.

PARP Inhibitors: The Highest-Concern Interaction

PARP inhibitors (olaparib, niraparib, rucaparib, talazoparib) trap PARP1 at DNA damage sites, preventing single-strand break repair in BRCA-mutated tumor cells. These drugs require NAD+ as a substrate for poly(ADP-ribosyl)ation.

Preclinical data support this concern. In Brca2-mutated mouse mammary tumors, loss of PAR glycohydrolase (PARG) restored PAR formation, partially rescued PARP1 signaling and was identified as a major mechanism of PARP inhibitor resistance 3. No controlled human data exist for combining NAD+ precursors with PARP inhibitors.

The clinical guidance is direct: patients on any PARP inhibitor should not take NMN or NR without explicit oncologist approval. This applies to maintenance therapy as well as active treatment phases.

Alkylating Agents and Platinum Chemotherapies

Cisplatin, carboplatin, cyclophosphamide, and temozolomide induce DNA damage that activates PARP1-mediated NAD+ consumption. This "NAD+ depletion" is part of how these drugs trigger cancer cell death. Supplying exogenous NAD+ precursors during treatment could buffer tumor cells against this metabolic stress 4.

An opposing effect has also been documented. Axon degeneration after nerve injury or chemotherapy is driven by SARM1, an injury-activated NADase, and blocking SARM1 with gene therapy kept transected axons intact in mice 5. This dual-edged pharmacology makes the interaction unpredictable. Until human co-administration data clarify the tumor-vs-host selectivity, oncology patients should avoid NMN and NR during active chemotherapy cycles.

Antidiabetic Medications: Insulin, Sulfonylureas, and Metformin

Yoshino et al. (Science 2021, N=25) demonstrated that 250 mg/day NMN for 10 weeks improved skeletal muscle insulin sensitivity by approximately 25% in postmenopausal women with prediabetes, measured by hyperinsulinemic-euglycemic clamp 6. This insulin-sensitizing effect creates additive hypoglycemia risk when combined with sulfonylureas (glipizide, glimepiride), insulin, or other agents that lower blood glucose through independent mechanisms.

The interaction with metformin is more nuanced. Metformin activates AMPK, which increases NAD+ via the NAMPT salvage pathway. NMN also raises NAD+, potentially creating a synergistic SIRT1 activation loop. A 2019 Aging Cell trial found that metformin blunted the muscle hypertrophy response to resistance training in older adults and increased AMPK signaling 7. Whether NMN co-administration modifies metformin's metabolic benefits or risks in diabetic patients is untested.

Practical recommendation: patients on insulin or sulfonylureas who add NMN or NR should increase glucose monitoring frequency for the first 4 to 6 weeks. A 10 to 20% dose reduction in secretagogues may be warranted if fasting glucose drops below 70 mg/dL.

Figure 1

Fasting glucose before and after 10 weeks of NMN or placebo in women with prediabetes

Fasting glucose before and after 10 weeks of NMN or placebo in women with prediabetesBar chart of mean fasting plasma glucose in the 10-week NMN trial. Placebo group (12 women): 5.7 mmol/L before and 5.6 mmol/L after. NMN 250 mg a day group (13 women): 5.7 mmol/L before and 5.6 mmol/L after. The difference between groups was not significant.BeforeAfter 10 weeksPlacebo (12 women)5.7 mmol/L5.6 mmol/LNMN 250 mg a day (13 women)5.7 mmol/L5.6 mmol/L0246Mean fasting plasma glucose (mmol/L)
Fasting glucose before and after 10 weeks of NMN or placebo in women with prediabetesBar chart of mean fasting plasma glucose in the 10-week NMN trial. Placebo group (12 women): 5.7 mmol/L before and 5.6 mmol/L after. NMN 250 mg a day group (13 women): 5.7 mmol/L before and 5.6 mmol/L after. The difference between groups was not significant.BeforeAfter 10 weeksPlacebo (12 women)5.7 mmol/L5.6 mmol/LNMN 250 mg a day (13 women)5.7 mmol/L5.6 mmol/L0246Mean fasting plasma glucose (mmol/L)
From the 10-week randomized trial this page cites (Yoshino et al.): 13 women took NMN 250 mg a day and 12 took placebo. Mean fasting glucose went from 5.7 to 5.6 mmol/L (about 103 to 101 mg/dL) in both groups, and the authors found no NMN effect on it, even though muscle insulin sensitivity measured by clamp was 25% higher after NMN. The women had prediabetes, so the trial does not show what NMN does alongside insulin or a sulfonylurea. Source: Yoshino et al., Science 2021, results (full text), Table 1 (full text), Table 1 footnote (full text) [6].
Show the numbers behind this chart
Fasting glucose before and after 10 weeks of NMN or placebo in women with prediabetes
GroupBefore (mmol/L)After 10 weeks (mmol/L)
Placebo (12 women)5.75.6
NMN 250 mg a day (13 women)5.75.6

Anticoagulants and Antiplatelet Agents

NAD+ is a cofactor in redox reactions that regulate platelet activation and endothelial nitric oxide production.

NAD+'s role in platelet activation creates a theoretical additive bleeding risk with warfarin, direct oral anticoagulants (apixaban, rivarelbaban, edoxaban), and antiplatelet drugs (clopidogrel, ticagrelor). No case reports of clinically significant bleeding attributed to NMN or NR co-administration have been published as of May 2026.

For patients on warfarin, INR should be checked 2 weeks after starting or stopping NMN/NR. DOAC users should watch for unusual bruising, gum bleeding, or prolonged bleeding from minor cuts during the first month of co-administration.

Immunosuppressants: Calcineurin Inhibitors and mTOR Inhibitors

Tacrolimus and cyclosporine suppress T-cell activation through calcineurin inhibition. Raising NAD+ with NMN could theoretically shift the immune balance in transplant recipients, though the direction of this shift (immunostimulatory vs. regulatory) depends on context.

A more concrete concern exists with mTOR inhibitors (sirolimus, everolimus). SIRT1 activation inhibits mTOR signaling through TSC2 deacetylation and AMPK activation.

Transplant recipients and autoimmune patients on calcineurin or mTOR inhibitors should not add NMN or NR without transplant-team oversight. Trough drug levels should be checked within 2 weeks of any change.

Niacin and Other NAD+ Precursors

Nicotinic acid (niacin) and nicotinamide are older NAD+ precursors that share the downstream metabolic pathway. Combining NMN or NR with high-dose niacin (1,000 to 2,000 mg/day, used for dyslipidemia) risks NAD+ overload and excessive nicotinamide accumulation. Nicotinamide inhibits SIRT1 in vitro even at physiological concentrations 8.

Stacking multiple NAD+ precursors is pharmacologically redundant and potentially counterproductive. Patients should choose one precursor at a time.

Alcohol and Hepatotoxic Drugs

Ethanol metabolism consumes large amounts of NAD+ via alcohol dehydrogenase and aldehyde dehydrogenase. Alcohol use is not a contraindication. That should not be interpreted as license to drink heavily while supplementing.

For acetaminophen, the interaction is more concerning at overdose thresholds. NAPQI detoxification depends on glutathione, which is regenerated by NAD+-dependent pathways. At therapeutic acetaminophen doses (under 3 g/day), no interaction is expected. At supratherapeutic doses, the effect of NMN on NAPQI handling is unknown.

Cardiovascular Drugs: Statins, ACE Inhibitors, and Beta-Blockers

No mechanistic basis for a significant interaction exists between NMN/NR and HMG-CoA reductase inhibitors (statins), ACE inhibitors, or beta-blockers. NAD+ does not compete with the binding sites or metabolic pathways of these drug classes.

One theoretical benefit has been explored: NR at 1,000 mg/day for 6 weeks reduced systolic blood pressure by 3.2 mmHg in a small (N=30) crossover trial published in Nature Communications in 2018 9. This modest hypotensive effect is unlikely to cause symptomatic hypotension when added to antihypertensives, but patients on multi-drug blood pressure regimens should monitor readings for 2 to 4 weeks after starting NR or NMN.

Figure 2

Blood pressure on NR 1,000 mg a day compared with placebo after 6 weeks

Blood pressure on NR 1,000 mg a day compared with placebo after 6 weeksBar chart of mean blood pressure change on NR compared with placebo. All 24 participants: systolic 3.9 mmHg lower and diastolic 2.0 mmHg lower, not significant after correction. Post-hoc subgroup with systolic pressure 120 to 139 mmHg (13 people): systolic 9 mmHg lower. Subgroup with normal pressure (11 people): no change observed.Systolic, all 24 participants−3.9 mmHgDiastolic, all 24 participants−2.0 mmHgSystolic, 13 with pressure 120–139 (post-hoc)−9.0 mmHgSystolic, 11 with normal pressure (post-hoc)no change observed−10−505Change on NR compared with placebo (mmHg)
Blood pressure on NR 1,000 mg a day compared with placebo after 6 weeksBar chart of mean blood pressure change on NR compared with placebo. All 24 participants: systolic 3.9 mmHg lower and diastolic 2.0 mmHg lower, not significant after correction. Post-hoc subgroup with systolic pressure 120 to 139 mmHg (13 people): systolic 9 mmHg lower. Subgroup with normal pressure (11 people): no change observed.Systolic, all 24 participants−3.9 mmHgDiastolic, all 24 participants−2.0 mmHgSystolic, 13 with pressure 120–139 (post-hoc)−9.0 mmHgSystolic, 11 with normal pressure (post-hoc)no change observed−10−505Change on NR compared with placebo (mmHg)
From the crossover trial this page cites (Martens et al.): 24 healthy middle-aged and older adults took NR 500 mg twice a day and placebo for 6 weeks each. Across everyone, systolic pressure was 3.9 mmHg and diastolic 2.0 mmHg lower on NR, but neither difference was statistically significant after correction. A post-hoc look at the 13 people with systolic pressure of 120 to 139 found systolic 9 mmHg lower, and no change in the 11 with normal pressure; the authors say no statistical conclusions can be drawn from that split. Source: Martens et al., Nat Commun 2018, introduction (full text), Fig. 3 legend (full text), results (full text) [9].
Show the numbers behind this chart
Blood pressure on NR 1,000 mg a day compared with placebo after 6 weeks
Measure and groupChange on NR vs placebo (mmHg)
Systolic, all 24 participants−3.9
Diastolic, all 24 participants−2.0
Systolic, 13 with pressure 120–139 (post-hoc)−9.0
Systolic, 11 with normal pressure (post-hoc)no change observed

Psychiatric Medications: SSRIs, Benzodiazepines, and Stimulants

NAD+ participates in tryptophan metabolism via the kynurenine pathway, which intersects with serotonin synthesis. Theoretically, increasing NAD+ flux through the kynurenine pathway could divert tryptophan away from serotonin production. No clinical evidence supports a meaningful interaction between NMN/NR and SSRIs, SNRIs, or tricyclic antidepressants at standard supplementation doses.

Benzodiazepines and stimulants (amphetamine, methylphenidate) are metabolized by CYP3A4 and CYP2D6, respectively. NMN and NR show no inhibitory or inducing activity at these enzymes in available in vitro data. No dose adjustment is expected.

Monitoring Framework for Clinicians

The Endocrine Society has not published formal guidelines on NAD+ precursor supplementation as of 2026.

For patients on no interacting medications, NMN at 250 to 500 mg/day or NR at 300 to 600 mg/day has shown acceptable safety across 10 published human trials with durations of 6 to 12 weeks.

Frequently asked questions

Can I take NMN with metformin?
Yes, but monitor blood glucose closely. Both NMN and metformin improve insulin sensitivity through overlapping NAD+/AMPK pathways. The combination could lower fasting glucose more than either alone. Check glucose weekly for the first 6 weeks.
Does NMN interact with blood thinners like warfarin?
Possibly. NAD+-driven SIRT1 activation may reduce platelet aggregation, creating additive bleeding risk. Check INR 2 weeks after starting or stopping NMN. No clinical bleeding events have been reported, but caution is warranted.
Is it safe to take NMN during chemotherapy?
No, not without oncologist approval. NMN may restore PARP-mediated DNA repair in cancer cells, potentially reducing the effectiveness of PARP inhibitors, alkylating agents, and platinum chemotherapies.
Can NMN cause low blood sugar?
NMN improved insulin sensitivity by about 25% in a small trial (Yoshino 2021, N=25). For people on insulin or sulfonylureas, this could cause hypoglycemia. Those not on diabetes medications are unlikely to experience clinically low glucose.
Should I stop NMN before surgery?
Consider stopping NMN 7 days before elective surgery due to its mild antiplatelet effect. Discuss with your surgeon, especially if you are also on anticoagulants or antiplatelet drugs.
Does NMN affect the liver?
NMN has shown hepatoprotective effects in animal models of alcohol-induced liver injury. In human trials up to 12 weeks, no significant transaminase elevations were reported. Baseline liver function tests are still recommended.
Can I take NMN and NR together?
This is not recommended. Both convert to NAD+ through the same downstream pathway. Stacking them increases nicotinamide accumulation, which at high levels inhibits SIRT1 and defeats the purpose of supplementation.
Does NMN interact with antidepressants?
No clinically significant interaction has been identified. NMN does not inhibit CYP2D6 or CYP3A4, the primary enzymes that metabolize SSRIs and SNRIs. The theoretical tryptophan-diversion concern has not been observed in humans.
How does NMN work in the body?
NMN is converted to NAD+ by NMNAT enzymes in the nucleus, cytoplasm, and mitochondria. NAD+ then activates sirtuins, PARPs, and CD38, which regulate DNA repair, energy metabolism, inflammation, and cellular aging.
What is the difference between NMN and NR?
NR is phosphorylated by NR kinases to become NMN, which is then converted to NAD+. NR has more published human clinical data and FDA GRAS status. NMN was removed from the dietary supplement definition by FDA in November 2022.
Does NMN interact with thyroid medication?
No known interaction exists between NMN and levothyroxine or liothyronine. NAD+ metabolism does not affect thyroid hormone absorption, binding, or deiodination. Standard spacing rules for levothyroxine (empty stomach, 30-60 minutes before food) still apply.
What blood tests should I get before taking NMN?
Recommended baseline labs include fasting glucose, HbA1c, hepatic transaminases (ALT, AST), CBC with differential, and INR if on anticoagulants. Repeat at 8 weeks. Lipid panels are optional but informative.

References

  1. Yoshino J, Baur JA, Imai SI. NAD+ intermediates: the biology and therapeutic potential of NMN and NR. Cell Metab. 2018;27(3):513-528. PubMed
  2. Lord CJ, Ashworth A. PARP inhibitors: synthetic lethality in the clinic. Science. 2017;355(6330):1152-1158. PubMed
  3. Gogola E, et al. Selective loss of PARG restores PARylation and counteracts PARP inhibitor-mediated synthetic lethality. Cancer Cell. 2018;33(6):1078-1093.e12. PubMed
  4. Navas LE, Carnero A. NAD+ metabolism, stemness, the immune response, and cancer. Signal Transduct Target Ther. 2021;6(1):2. PubMed
  5. Geisler S, et al. Gene therapy targeting SARM1 blocks pathological axon degeneration in mice. J Exp Med. 2019;216(2):294-303. PubMed
  6. Yoshino M, Yoshino J, Kayser BD, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;372(6547):1224-1229. PubMed
  7. Walton RG, et al. Metformin blunts muscle hypertrophy in response to progressive resistance exercise training in older adults. Aging Cell. 2019;18(6):e13039. PubMed
  8. Bitterman KJ, Anderson RM, Cohen HY, et al. Inhibition of silencing and accelerated aging by nicotinamide. J Biol Chem. 2002;277(47):45099-45107. PubMed
  9. Martens CR, 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. PubMed
  10. Gaudineau C, Auclair K. Inhibition of human P450 enzymes by nicotinic acid and nicotinamide. Biochem Biophys Res Commun. 2004. PMID 15081432.
Evidence overview for nad nmn: NMN and NR Drug Interactions: A Complete Clinical Profile