Can you take NAD+ with retatrutide? It is a question gaining traction as interest in both NAD+ precursor supplements and next-generation weight-loss medicines grows. NAD+ supplements — typically taken as nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN) — are marketed to support cellular energy and healthy ageing. Retatrutide is an investigational triple receptor agonist not yet approved by the MHRA or EMA. Because both substances influence metabolic pathways, understanding the potential risks, regulatory context, and when to seek professional advice is essential before considering this combination.

What Are NAD+ Supplements and Retatrutide?

NAD+ supplements (typically NR or NMN) raise cellular coenzyme levels, whilst retatrutide is an unlicensed investigational triple receptor agonist (GLP-1, GIP, glucagon) not yet approved by the MHRA or EMA for use in the UK.

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found naturally in every cell of the body. It plays a central role in energy metabolism, DNA repair, and cellular signalling. As NAD+ levels naturally decline with age, supplements designed to raise these levels — typically through precursors such as nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN) — have grown in popularity.^[14][15]

It is important to note that these two precursors have different regulatory statuses in the UK. Nicotinamide riboside (NR) has been authorised as a novel food by the European Food Safety Authority (EFSA) and is available as a food supplement in the UK.^[1][2] Nicotinamide mononucleotide (NMN), however, is classified as a novel food that has not been authorised for sale as a food supplement in Great Britain; products containing NMN as a supplement ingredient are therefore not lawfully sold for this purpose in the UK.^[2] Consumers should check the Food Standards Agency (FSA) novel food authorisation list before purchasing any NAD+ precursor product. The clinical evidence base for health claims associated with either precursor remains limited and inconsistent.

Retatrutide is a novel investigational medicine currently in clinical development. It is a triple receptor agonist, targeting the glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon receptors simultaneously. This triple-action mechanism distinguishes it from existing licensed medicines such as semaglutide (Wegovy®/Ozempic®) and tirzepatide (Mounjaro®). A Phase 2 clinical trial published in the New England Journal of Medicine (2023) reported substantial reductions in body weight and improvements in metabolic markers, generating considerable interest; however, these findings represent early-phase evidence and cross-trial comparisons with licensed agents should be interpreted with caution.^[3]

As of mid-2025, retatrutide has not been approved by the Medicines and Healthcare products Regulatory Agency (MHRA) or the European Medicines Agency (EMA) for use in the UK or Europe. It remains an experimental compound available only within regulated clinical trials. Any individual claiming to supply or use retatrutide outside of a regulated trial setting is doing so outside approved medical and legal frameworks. The MHRA advises consumers of the significant risks associated with purchasing unlicensed medicines online, including the risk of counterfeit or mislabelled products.

Known Interactions Between NAD+ and Retatrutide

No published pharmacokinetic or pharmacodynamic interaction data exist between NAD+ precursors and retatrutide, but overlapping metabolic effects and shared gastrointestinal side effects mean the combination cannot be considered risk-free.

At present, there is no published evidence of a direct pharmacokinetic or pharmacodynamic interaction between NAD+ precursor supplements and retatrutide. This is largely because retatrutide has not yet completed the full regulatory approval process, and comprehensive drug interaction studies — particularly those involving commonly used supplements — have not been publicly reported.

However, the absence of documented interactions does not mean that combining these substances is without risk. Several considerations are worth noting:

• Metabolic overlap: Both NAD+ precursors and retatrutide influence metabolic pathways. NAD+ is integral to mitochondrial function and energy production, whilst retatrutide modulates insulin secretion, glucagon activity, and energy expenditure. Whether these overlapping effects produce additive, synergistic, or antagonistic outcomes in humans is not established.

• Gastrointestinal effects: Retatrutide, like other GLP-1 receptor agonists, commonly causes nausea, vomiting, and reduced appetite, as documented in the SmPCs for licensed GLP-1-based medicines such as semaglutide and tirzepatide.^[5][6] Some individuals taking NAD+ precursors also report gastrointestinal discomfort. Combining the two could theoretically worsen these symptoms, though this has not been formally studied.

• Blood glucose effects: Retatrutide has glucose-lowering properties. Some early research has examined whether NR or NMN may influence insulin sensitivity, but human evidence is limited and inconsistent; no clinically meaningful glucose-lowering effect from NAD+ precursors alone has been established. Nevertheless, caution is warranted in individuals with diabetes or those at risk of hypoglycaemia, particularly if they are also taking insulin or a sulfonylurea.

Given the lack of robust interaction data, any decision to combine NAD+ supplements with retatrutide — or any GLP-1-based therapy — should be discussed with a qualified healthcare professional.

How Retatrutide Works and Why Combinations Matter

Retatrutide simultaneously activates GLP-1, GIP, and glucagon receptors, producing broad effects on weight, blood glucose, and lipid metabolism that make concurrent use of metabolically active supplements such as NAD+ precursors more complex.

Understanding retatrutide's mechanism of action helps clarify why combining it with other metabolically active substances requires careful thought. Retatrutide acts as a triple incretin receptor agonist, simultaneously activating three distinct receptors:

• GLP-1 receptors — stimulating insulin secretion in a glucose-dependent manner, slowing gastric emptying, and reducing appetite

• GIP receptors — enhancing insulin release and potentially improving fat metabolism

• Glucagon receptors — increasing energy expenditure and promoting fat breakdown in the liver

This multi-receptor activity produces pronounced effects on body weight, blood glucose, lipid metabolism, and hepatic fat. In the Phase 2 clinical trial published in the New England Journal of Medicine (2023), participants receiving retatrutide achieved mean weight reductions of up to approximately 24% over 48 weeks. These are early-phase findings; direct comparisons with licensed agents across different trials should be treated with caution, as trial populations, designs, and endpoints differ.

Because retatrutide exerts such broad metabolic effects, introducing additional substances that also influence energy metabolism, insulin sensitivity, or cellular signalling — as NAD+ precursors may do — creates a more complex physiological picture. The liver is central to both NAD+ metabolism and the glucagon-mediated actions of retatrutide. Theoretical interactions at the hepatic level cannot be ruled out without dedicated research, and this possibility should be regarded as a hypothesis pending further study.

Retatrutide also delays gastric emptying, which may affect the timing of absorption of orally administered supplements, including NAD+ precursors. The clinical significance of this effect on supplement uptake has not been directly studied. Patients should be aware that the pharmacological profile of triple agonist therapies is still being characterised, and a cautious approach to concurrent supplement use is reasonable.

Safety Considerations When Combining Supplements with GLP-1 Medicines

GLP-1-based medicines slow gastric emptying, suppress appetite, and carry rare risks of pancreatitis and gallbladder disease; dietary supplements are not subject to the same pre-market safety testing as licensed medicines, increasing uncertainty when combined.

Even where specific interaction data are unavailable, broader safety principles apply when combining dietary supplements with any GLP-1-based medicine, including investigational agents such as retatrutide.

Delayed gastric emptying and absorption timing: GLP-1 receptor agonists slow gastric emptying, as noted in the SmPCs for semaglutide and tirzepatide.^[5][6] This may affect the timing of absorption of orally taken supplements and medicines. The clinical significance is generally modest, but caution is warranted for medicines with a narrow therapeutic index. NAD+ precursors are water-soluble, and whilst delayed gastric emptying may affect the timing of their uptake, a major effect on overall absorption efficiency has not been established.

Nutritional intake: Significant appetite suppression associated with GLP-1 therapies can lead to reduced overall dietary intake. This may increase the general risk of inadequate micronutrient intake over time. Patients are advised to maintain as balanced a diet as possible and to discuss nutritional monitoring with their healthcare team if appetite suppression is marked. Since NAD+ synthesis depends on adequate dietary niacin (vitamin B3) and tryptophan, overall nutritional status is relevant in this context.^[12][13]

Rare but serious class effects: GLP-1-based therapies are associated with rare but serious adverse effects, including pancreatitis and gallbladder disease, as noted in the SmPCs for licensed agents in this class.^[5][6] Patients should be aware of these risks and seek prompt medical attention if they develop severe or persistent abdominal pain.

Quality and regulation of supplements: In the UK, dietary supplements are regulated as food supplements under the Food Supplements (England) Regulations 2003. They are not subject to the same rigorous pre-market safety and efficacy testing as licensed medicines. Product quality, dosage accuracy, and purity can vary considerably between brands. This regulatory gap means that patients may be taking supplements of uncertain composition alongside a potent investigational drug.

Individual variability: Factors such as age, hepatic health, and concurrent medications all influence how the body processes both supplements and medicines. The renal clearance profile of retatrutide has not been fully characterised in published data; patients with significant renal or hepatic impairment should seek specific advice from their clinical team before taking any supplement alongside an investigational medicine.

What UK Clinical Guidance Says About Supplement Use

NICE and NHS guidance does not recommend NAD+ precursors as part of weight management strategies, and the MHRA advises that purchasing retatrutide outside a regulated clinical trial is not legally sanctioned in the UK.

UK clinical guidance does not currently address the specific combination of NAD+ supplements and retatrutide, primarily because retatrutide remains unlicensed and is not part of standard NHS prescribing practice. However, broader guidance from NICE and NHS sources offers relevant principles.

NICE has published technology appraisals for licensed GLP-1-based medicines used in weight management, including TA875 (semaglutide 2.4 mg for managing overweight and obesity). These appraisals emphasise an evidence-based, whole-person approach to treatment. NICE guidance does not recommend routine supplementation with NAD+ precursors as part of weight management or metabolic health strategies, reflecting the limited and inconsistent clinical evidence currently available for these products.

The NHS advises patients to inform their GP or specialist of all supplements and over-the-counter products they are taking, particularly when commencing new prescribed or trial medicines. Even seemingly benign supplements can interact with medicines or complicate clinical monitoring. For individuals enrolled in clinical trials of retatrutide, trial protocols typically require full disclosure of all concurrent supplement use, and some protocols may restrict or prohibit certain supplements during the trial period. Participants should notify their study team before starting any new supplement and report any adverse effects in accordance with the trial protocol.

The MHRA has not issued specific guidance on NAD+ supplements in the context of GLP-1 therapies, but its broader messaging encourages consumers to exercise caution with unregulated products and to seek professional advice before combining supplements with any medicine. The MHRA also advises that purchasing retatrutide outside of a regulated clinical trial is not legally sanctioned in the UK, and products sold online claiming to be retatrutide may be counterfeit, mislabelled, or unsafe.

If you experience a suspected side effect from any medicine or supplement, you can report it to the MHRA via the Yellow Card Scheme at yellowcard.mhra.gov.uk.

When to Speak to a GP or Pharmacist Before Combining

Professional advice is essential before combining NAD+ supplements with any GLP-1-based therapy, particularly for people with diabetes, liver or kidney disease, or those enrolled in a clinical trial, where supplement use may affect trial validity or safety.

Given the uncertainties outlined above, speaking to a GP or pharmacist before combining NAD+ supplements with retatrutide — or any GLP-1-based therapy — is strongly advisable. There are specific circumstances in which professional advice is particularly important:

• Before starting any new supplement whilst enrolled in a clinical trial or taking a GLP-1 medicine, as this may affect trial validity or treatment safety

• If you have diabetes, as retatrutide has glucose-lowering properties and, if you are also taking insulin or a sulfonylurea, the risk of hypoglycaemia requires careful management

• If you have liver or kidney disease, since both NAD+ metabolism and retatrutide's glucagon-mediated actions involve hepatic pathways; discuss any supplement use with your clinical team

• If you are taking other prescribed medicines, particularly those with a narrow therapeutic index, as delayed gastric emptying associated with GLP-1 therapies may affect their absorption

Seek urgent medical attention — contact NHS 111 or go to an urgent care centre — if you experience any of the following whilst taking a GLP-1-based medicine:

• Severe or persistent abdominal pain (which may rarely indicate pancreatitis or gallbladder disease)

• Persistent vomiting or inability to keep fluids down, which can lead to dehydration

• Symptoms of hypoglycaemia (shakiness, sweating, confusion, or palpitations), particularly if you are also taking insulin or a sulfonylurea

A pharmacist is an accessible first point of contact for supplement-related queries and can advise on potential interactions, product quality, and appropriate dosing. GPs can review the broader clinical picture, particularly for patients with complex health histories.

Whilst there is no established contraindication to taking NAD+ supplements alongside GLP-1 therapies based on current evidence, the absence of safety data is not the same as confirmed safety. A cautious, informed approach — guided by a healthcare professional — remains the most appropriate course of action for anyone considering this combination. Suspected side effects from any medicine or supplement should be reported to the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk.

Frequently Asked Questions