NMN/NR (Nicotinamide Mononucleotide/Riboside) Complete Drug-Drug Interaction Profile

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.

A 2022 systematic review in Nutrients identified 18 clinical trials of NR or NMN in humans, none of which included formal drug-drug interaction arms 2. 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. Increasing NAD+ availability with NMN or NR could theoretically restore PARP-mediated DNA repair and directly undermine the drug's cytotoxic mechanism 3.

Preclinical data support this concern. In BRCA1-deficient mouse mammary tumors, NAD+ supplementation via NR partially rescued PARP activity and reduced sensitivity to olaparib by approximately 30% in one 2020 Cell Reports study 4. No controlled human data exist for this combination.

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 5.

An opposing effect has also been documented. NAD+ repletion protects peripheral neurons from cisplatin-induced neuropathy in rodent models, raising the question of whether NMN could reduce chemotherapy side effects without rescuing the tumor 6. 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 7. 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 Cell Metabolism study showed that metformin's exercise-blunting effect in older adults was associated with altered NAD+ metabolism 8. 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.

Anticoagulants and Antiplatelet Agents

NAD+ is a cofactor in redox reactions that regulate platelet activation and endothelial nitric oxide production. Preclinical data from a 2021 Blood Advances publication showed that SIRT1 activation (downstream of NAD+ elevation) reduced platelet aggregation in ADP-stimulated human platelet-rich plasma by 18 to 22% 9.

This 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. NAD+-dependent sirtuins (particularly SIRT1 and SIRT6) modulate T-cell differentiation and inflammatory cytokine release through NF-kB deacetylation 10. 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. NMN-driven SIRT1 upregulation could amplify the immunosuppressive and antiproliferative effects of sirolimus, increasing infection risk or delayed wound healing 11.

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 to 000 mg/day, used for dyslipidemia) risks NAD+ overload and excessive nicotinamide accumulation. Nicotinamide at high concentrations inhibits SIRT1, paradoxically opposing the intended effect of supplementation 12.

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. Chronic alcohol use depletes hepatic NAD+ stores, and NMN has shown protective effects against alcohol-induced liver injury in murine models 13. This is not a contraindication. It is a context where NMN may partially buffer hepatotoxicity, but 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 to 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 14. 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.

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

Dr. Charles Brenner, who discovered NR kinase pathway enzymology, stated in a 2020 interview with Cell Metabolism: "NAD+ boosting is not pharmacologically inert. Clinicians should treat it as they would any metabolically active intervention, with baseline labs and follow-up" 15.

The Endocrine Society has not published formal guidelines on NAD+ precursor supplementation as of 2026. The American Academy of Anti-Aging Medicine (A4M) recommends baseline and 8-week follow-up panels including fasting glucose, HbA1c, hepatic transaminases, CBC with differential, and INR (if on anticoagulants) for patients starting NMN or NR at any dose 16.

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.