NAD Injections UK: Do They Work? Evidence and Safety

You're wiped out by three in the afternoon. The weight that used to shift with a bit of effort now doesn't budge. And somewhere between a wellness reel and a clinic price list, you've come across NAD injections, promising to top up your cells, clear the fog and wake your metabolism back up.

It's a persuasive pitch, and the biology behind it is genuinely interesting. What matters is the gap between that biology and what has actually been tested in people. So here's the honest version: what NAD+ does, what the research has really shown, and what to do instead if you're tired and trying to lose weight.

What NAD+ actually does in your cells

Nicotinamide adenine dinucleotide sits at the centre of your energy metabolism. Every cell in your body uses it, shuttling between two forms (NAD+ and NADH) to carry electrons through the reactions that convert what you eat into usable fuel. Without it, your mitochondria stop making ATP, and everything else stops with them.

It has a second job too. NAD+ is the fuel for a family of enzymes called sirtuins, and for the PARPs involved in repairing damaged DNA. Both are bound up with how cells respond to stress and how they age.

Here's the bit that launched an industry: NAD+ levels decline with age. That observation is real, and it's reproducible across tissues. The leap that follows, that topping NAD+ back up will therefore reverse the things we associate with ageing, is where the evidence thins out considerably.

Are NAD injections licensed in the UK?

No. This is the single most important thing to understand before you book anything.

NAD+ injections and infusions hold no UK marketing authorisation. They're supplied under the MHRA's rules for unlicensed medicinal products, known as "specials", which means the product is made or imported for one named patient, ordered by a prescriber, and never assessed by the regulator for quality, safety or efficacy in the way a licensed medicine is.

That's not automatically sinister. Specials are used sensibly every day in paediatrics, psychiatry and palliative care, usually because no licensed alternative exists for a particular patient. But the GMC is explicit about the bar a prescriber has to clear: they must be satisfied there is sufficient evidence or experience of using the medicine to demonstrate its safety and efficacy, take responsibility for the prescription, and oversee your follow-up.

Ask yourself whether that bar is being cleared when NAD+ is offered from a treatment menu, priced per session, to someone who walked in tired.

What the evidence actually shows

The claims made for NAD injections are broad. The human trial evidence behind them, specifically for injected NAD+, is thin to non-existent.

Where decent human data does exist, it's for the oral precursors. In a randomised, double-blind, placebo-controlled trial of 120 healthy adults aged 60 to 80, a nicotinamide riboside combination raised whole-blood NAD+ by roughly 40% at the standard dose and roughly 90% at double dose after 30 days, and the increase held. The placebo group showed no rise at all.

That's a real, well-conducted result. Note what it does and doesn't tell you. It shows an oral supplement can raise a blood marker. It doesn't show that people felt better, lost weight, or aged more slowly. And it says nothing about injections, because injections weren't studied.

This distinction gets blurred constantly in marketing copy. A clinic will cite precursor research to justify an infusion, as though the delivery route were a detail. It isn't. How much NAD+ actually reaches tissue after an injection, how long it stays there, and what it does once it's there are questions that haven't been properly answered in humans.

Do NAD injections help with weight loss?

Not on any evidence we have. It's a question people ask us often, usually in some version of "is NAD like Ozempic?". It isn't, and the two aren't close.

NAD+ appears in the same textbook chapters as glucose and lipid metabolism, which is where the metabolic claims come from. That's a mechanism, not a result. No published trial has shown that NAD injections reduce body weight in people.

Compare that with what sits on the other side of the ledger. Tirzepatide has trial data in tens of thousands of participants: in the SURMOUNT-1 trial, people on the highest dose lost around 21% of their body weight over 72 weeks. NICE recommended it for managing overweight and obesity in December 2024. Whatever you think about weight-loss injections, that's a completely different evidence base from a therapy with no controlled human trials at all.

If you want the mechanism explained properly, our guide to how GLP-1 medications work covers it, and the main weight-loss injections available in the UK sets out what each one is licensed for.

The same test applies to everything marketed alongside NAD+. We've applied it to berberine, to appetite suppressants and to weight-loss supplements generally, and the answer is usually the same. Interesting mechanism, modest or absent human results, confident marketing.

Oral NAD+ supplements versus injections: does the route matter?

This is the argument every clinic makes, so it's worth unpicking properly.

The pitch goes like this. Swallow a capsule and it has to survive your stomach, cross the gut wall and pass through the liver before any of it reaches your bloodstream. Inject it and you skip all of that, so more of it gets where it's needed. Bypassing first-pass metabolism is a real pharmacological principle, and for plenty of drugs it's exactly why we inject them.

The trouble is that NAD+ itself is a large, charged molecule. It doesn't stroll across cell membranes. The current understanding is that circulating NAD+ is largely broken down into smaller precursors before cells take anything up, which means an injection may end up delivering much the same building blocks as a capsule, just faster and far more expensively. Whether that's what happens in people, and how long any tissue-level change lasts, hasn't been properly established.

So we're left with an odd situation. The delivery route with the theoretical advantage has almost no human data. The delivery route with the human data, oral precursors like nicotinamide riboside and nicotinamide mononucleotide, is the one clinics tend to dismiss as inferior.

There's also a practical difference nobody mentions in the consultation. Oral precursors are sold as food supplements at supermarket prices and you take them at home. Injections require a clinic visit, a prescriber, and in the case of infusions, a few hours of your day. If the biological endpoint is similar, that's a substantial difference in cost and hassle for an unproven gain.

None of this makes injections useless. It makes them unstudied, which is a different problem, and one that only trials can fix. Until those exist, anyone telling you the injected route is definitively better is describing a hypothesis rather than a finding.

NAD injection side effects and safety

Because there are no large controlled trials, the side-effect profile comes from clinic reports and case experience rather than proper safety data. That's a limitation, not a reassurance.

Commonly reported with intramuscular or subcutaneous NAD injections:

• Pain, redness, swelling or bruising at the injection site
• Flushing and a feeling of warmth
• Nausea or mild stomach upset
• Headache or light-headedness
• Fatigue or restlessness for a day or so afterwards

Intravenous infusions add their own risks: infection at the cannula site, inflammation of the vein, and leakage into surrounding tissue. Rapid infusion is the main driver of the unpleasant stuff. Chest tightness, flushing and a jittery, anxious feeling are common enough that reputable clinics run NAD+ slowly, often over two to four hours. If a clinic offers to push it quickly, that's a reason to pause.

Anaphylaxis is uncommon but possible with any injectable, so the clinic should have adrenaline and trained staff on site.

Some groups should avoid NAD+ therapy altogether, mainly because nobody has studied it in them: during pregnancy or breastfeeding, in under-18s, and in anyone with an active cancer, given the theoretical concern about supporting cell metabolism. If you have heart, liver or kidney disease, or take regular medication, talk to your GP first. Interactions haven't been systematically studied, which means nobody can tell you there aren't any.

One practical point people miss: if you do have a bad reaction to an unlicensed treatment, you can and should report it through the MHRA's Yellow Card scheme. That's how safety signals for unlicensed products get picked up at all.

What NAD injections cost, and how often they're given

Two questions, one answer: it depends entirely on the clinic, because there's no licensed product and therefore no standard dose, schedule or price.

NAD+ therapy isn't NHS-funded, so you're paying privately. Intramuscular or subcutaneous shots are the cheaper end. IV infusions sit at the top, partly because you're paying for several hours of chair time and supervision. Most clinics sell courses rather than single sessions, which is where the real number lives.

We're deliberately not quoting a headline price here, because the figures advertised vary so widely between clinics that any single number would mislead you. What's more useful is knowing what to ask before you commit:

• What does a full course cost, in writing, not the price of one session?
• How many sessions before I should expect anything, and what happens if I don't?
• Is there a top-up or maintenance schedule, and what does that cost annually?
• Is the consultation and any follow-up included?

On frequency, you'll see protocols ranging from weekly shots to a loading course of infusions followed by monthly maintenance. None of these schedules is evidence-based in the way a licensed medicine's dosing is. They're clinic conventions. Understanding that they're conventions rather than science makes it easier to judge what you're being sold.

Before booking anywhere, check the clinic is registered with the appropriate regulator: the Care Quality Commission in England, or Healthcare Improvement Scotland, Healthcare Inspectorate Wales, or the RQIA in Northern Ireland.

If you're exhausted and trying to lose weight, start here

This is the part that matters most, and it's the part the wellness industry skips.

Persistent tiredness is a symptom, not a diagnosis. It has a long list of common, treatable causes, and most of them show up on a fairly ordinary set of blood tests. NICE's guidance on tiredness in adults points to a first-line panel that usually includes a full blood count, ferritin, thyroid function, HbA1c, B12 and folate, liver and kidney function, inflammatory markers, and coeliac serology.

Iron deficiency, an underactive thyroid, undiagnosed type 2 diabetes, coeliac disease, depression, sleep apnoea. Any one of these will flatten you, and several of them also make weight harder to shift. Spending several hundred pounds on infusions while an unrecognised thyroid problem sits untreated is the outcome we'd most want you to avoid.

See your GP first. If something turns up, treating it will do more for your energy than any infusion.

It's also worth knowing that carrying extra weight is itself a common cause of the exhaustion people bring to wellness clinics, partly through disrupted sleep and undiagnosed sleep apnoea, partly through the metabolic strain. Patients often tell us the energy came back before the scale moved much, which makes sense once you understand the mechanism. Treating the weight can treat the tiredness. Treating the tiredness with an infusion does nothing for the weight.

If the bloods come back clear, the boring answers are still the ones with evidence behind them. Sleep, and specifically how much you're actually getting, and whether you snore or wake unrefreshed. Protein at breakfast rather than at dinner only. Some resistance training, twice a week, because muscle is metabolically expensive tissue and losing it is what makes fatigue and weight regain worse together. And stress, which does real measurable things to appetite and body composition. We've written about what stress actually does to weight if that one rings true.

None of that is glamorous. It's just what works.

And if your weight is the core problem rather than a side note, that's worth addressing directly, with treatment that has been through trials, rather than obliquely through a therapy that hasn't.

This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting any treatment.