NAD+ injections are a way of delivering nicotinamide adenine dinucleotide, the coenzyme every cell uses to make energy and repair DNA, directly into the body by a small subcutaneous injection. Because the molecule bypasses digestion, more of it reaches the bloodstream than with oral NMN or NR supplements, and the dose can be taken at home in under a minute.
This guide covers what NAD+ actually does, why levels fall with age, how an injection compares with IV drips and capsules, what a sensible at-home protocol looks like, what the research does and does not show, and what to check before buying anything in the UK. It is written for adults who are considering NAD+ for the first time and want the full picture before they start.
Educational content, not medical advice. NAD+ is not intended to diagnose, treat, cure or prevent any disease. Speak to a licensed prescriber before starting any injectable protocol, especially if you are pregnant or breastfeeding, have active or historic cancer, or take regular medication.
What is NAD+?
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell. It has two jobs that matter for how you feel day to day. First, it shuttles electrons during the reactions that turn food into ATP, the chemical energy your mitochondria produce. Second, it is the fuel for a family of enzymes, including the sirtuins and PARPs, that repair DNA, regulate inflammation and help set the circadian clock. For a longer explainer, read what NAD+ is and how it works.
Those two jobs compete for the same pool. When a cell is under stress, DNA-repair enzymes draw NAD+ down, and energy production has less to work with. That is one reason low NAD+ is associated with fatigue, slower recovery and the general feeling of running on a flat battery.
Why NAD+ levels fall with age
Tissue studies in humans show NAD+ declining steadily through adult life. Work published in PLoS ONE in 2012 measured skin samples across age groups and found levels in older adults at roughly half those of young adults, with a matching rise in oxidative damage. A 2019 analysis of plasma in Rejuvenation Research reported the same pattern in blood.
The decline has several causes operating at once:
- Higher consumption. Chronic inflammation activates CD38, an enzyme that breaks NAD+ down, and accumulated DNA damage keeps PARP enzymes busy.
- Lower production. The salvage pathway that recycles NAD+ (via the enzyme NAMPT) becomes less efficient.
- Lifestyle load. Poor sleep, alcohol, heavy training blocks and long-haul travel all draw on the same pool.
The practical point is that by the time most people reach their forties, their cells have less NAD+ available and more demand for it. That is the gap an NAD+ protocol is designed to address.
The three ways to raise NAD+: capsules, IV and injection
There are three broad routes. They differ far more in how much NAD+ reaches your cells, and in cost and convenience, than in the molecule itself.
| Route | What you take | Absorption | Where | Time per dose |
|---|---|---|---|---|
| Oral capsules | Precursors (NMN or NR) that the body must convert into NAD+ | Variable; much of the dose is broken down in the gut and liver | Home | Seconds |
| IV infusion | NAD+ itself, diluted in saline | Complete, but delivered over 2 to 4 hours to limit side effects | Clinic | Half a day including travel |
| Subcutaneous injection | NAD+ itself, in a pre-mixed cartridge or vial | High; bypasses digestion, absorbed from the fat layer under the skin | Home | About 30 seconds |
Oral precursors. NMN and NR have the most clinical trials behind them. A 2018 trial in Nature Communications showed that NR raises blood NAD+ in healthy middle-aged adults, and a 2021 study in Science found NMN improved muscle insulin sensitivity in prediabetic women. The limitation is conversion: you are taking a building block, and how much becomes NAD+ depends on your gut, liver and the enzymes mentioned above. We compare the two approaches in NAD+ injections vs NMN and NR supplements.
IV infusions. These deliver the whole molecule. A 2019 pilot study in Frontiers in Aging Neuroscience tracked plasma NAD+ during a six-hour infusion and confirmed that infused NAD+ is taken up by tissues rather than simply excreted. The trade-off is time and money: infusions run for hours, in a clinic, and cost several hundred pounds each. We compare the two directly in NAD+ injections vs IV drips.
Subcutaneous injections. A small volume of NAD+ is injected into the fat layer of the abdomen or thigh with a very fine needle. Absorption is slower than IV but still high, and because the dose is small and frequent rather than large and occasional, levels stay steadier through the week. This is the format The NAD Shop is built around.
How an at-home NAD+ injection works
Modern NAD+ injection kits borrow the hardware that people with diabetes and patients on GLP-1 medication have used for decades: a reusable auto-injector pen with a dial, pre-filled cartridges, and single-use micro-needles.
Each cartridge holds 500mg of NAD+ in 3ml. You dial the dose on the pen, attach a fresh needle, pinch a fold of skin and press. The pen's shield covers the needle, so you never see it, and a 32-gauge 6mm needle going into subcutaneous fat feels like a light pinch for most people. The whole ritual takes about thirty seconds. We walk through it in detail in how to inject NAD+ at home, step by step.
Some people prefer vials and a syringe over a pen. Vials hold 1000mg in 5ml and work out cheaper per milligram, but you measure the dose yourself in units rather than reading the pen's dial. The dosage calculator converts a target dose into the right mark for either device.
How much NAD+ to inject, and how often
Published subcutaneous protocols sit in a fairly narrow range, and most people land on 50mg per injection, with 25mg as a gentle first step if you want one.
| Phase | Dose | Frequency | Weekly total |
|---|---|---|---|
| Days 1 to 3 (loading) | 50mg (0.3ml, 30 clicks on the pen) | Once a day | Week 1: about 250mg |
| From day 4 | 50mg (0.3ml, 30 clicks on the pen) | Every other day, three or four a week | 150 to 200mg |
| Maintenance (after month 1, if it suits you) | 50mg | Twice a week | 100mg |
Starting low matters. The most common side effect of NAD+ is a transient feeling of warmth, flushing or mild nausea while the molecule is absorbed, and it is dose and speed dependent. If you want to test how you respond, take 25mg (0.15ml, 15 clicks on the pen) for the first one or two injections before moving to 50mg. Do not go above 100mg per injection or 500mg per week without a prescriber. A single 500mg cartridge gives ten 50mg doses, so a two-cartridge kit covers roughly five weeks at the usual rhythm.
Needs are individual. Body weight, training load, sleep debt and age all shift where you feel best. Confirm your own protocol with a prescriber, and adjust gradually rather than in jumps. The full protocol, with the pen and syringe mark for every dose, is in our NAD+ injection dosage guide.
What to expect, and when
NAD+ is not a stimulant, so the first thing most people notice is not a surge but an absence: less of the mid-afternoon slump, easier mornings. Based on what customers report to us and on the mechanism itself, a realistic timeline looks like this:
- Days 1 to 7. Many people notice sleep quality and morning energy first (the research behind both is in NAD+ for sleep and jet lag and NAD+ for energy and fatigue). Some feel nothing yet, which is normal.
- Weeks 2 to 4. Steadier focus through the day and faster recovery from training or late nights are the most commonly reported changes.
- Month 2 onwards. Benefits tied to sirtuin activity, such as skin quality and resilience under stress, build slowly and depend on consistency.
Individual responses vary widely, and NAD+ will not compensate for chronic sleep deprivation or an otherwise depleted lifestyle. Think of it as restoring a resource your cells draw on, not as adding a new one.
What the research shows, and what it does not
It is worth being precise here, because the marketing around NAD+ often runs ahead of the data.
Well established. NAD+ declines with age in human tissue and plasma. Raising NAD+ activates sirtuins and improves mitochondrial function in animal models. Oral precursors raise blood NAD+ in humans. Infused NAD+ is taken up by human tissue. The comprehensive 2021 review in Nature Reviews Molecular Cell Biology is the best single summary of the biology.
Promising but early. Human trials of NAD+ repletion show measurable improvements in specific markers, such as muscle insulin sensitivity, arterial stiffness and some cognitive measures, but the trials are small and short. A 2020 benefit-and-risk analysis in Experimental Gerontology concluded that NAD+ therapy is well tolerated and biologically plausible for age-related decline, while calling for larger studies.
Not established. There is no human evidence that NAD+ extends lifespan, reverses ageing or treats any specific disease. Anyone making those claims is ahead of the science.
Safety, side effects and who should not use NAD+
NAD+ has a long safety record in clinical use and the side effects of subcutaneous injection are mostly mild and short-lived:
- Warmth, flushing or tightness in the chest during absorption, usually easing within minutes. Injecting more slowly and using a smaller dose reduces it.
- Mild nausea or light-headedness, more common on an empty stomach.
- A small bump, redness or bruise at the injection site. Rotating sites prevents this.
Do not start NAD+ without medical advice if you are pregnant or breastfeeding, have active or historic cancer, have atrial fibrillation, are immunosuppressed or have had an organ transplant, or have Lyme disease. NAD+ is for adults only. What each side effect feels like, how long it lasts and how to reduce it is covered in NAD+ injection side effects.
What to check before buying NAD+ in the UK
The NAD+ market has grown quickly and quality varies. Before you buy from anyone, including us, check the following (the legal side is covered in is NAD+ legal in the UK?):
- Third-party purity testing. Ask for a certificate of analysis for the batch. NAD+ should test above 99% purity; ours is third-party verified at 99.5%.
- Pre-mixed and sterile. Powder you reconstitute yourself introduces contamination risk and dosing error. Pre-mixed cartridges or sealed vials remove both.
- Cold chain and storage guidance. NAD+ in solution degrades with heat and light. A serious supplier ships accordingly and tells you how to store it.
- Complete kits. You need sterile single-use needles, prep wipes and a sharps bin, not just the NAD+. Pharmacies and many councils accept full sharps bins for disposal.
- Human support. You will have questions in your first week. Make sure a person, not a bot, answers them.
Which kit to start with
- New to NAD+ and want to test the water: the NAD+ Trial Kit gives you the pen and one 500mg cartridge, enough for the loading week and a week beyond.
- Ready to run a full first month: the NAD+ Discovery Kit includes the pen and two 500mg cartridges, roughly five weeks of protocol.
- Comfortable with a syringe and want the lowest cost per milligram: the NAD+ Injection Kit, 2 × 1000mg ships two sealed vials with needles, wipes and a sharps bin, about two months of doses.
- Already own the pen: the Pen Refill Kit covers one, two or three months of cartridges.
Not sure between cartridges and vials? 500mg vs 1000mg NAD+ compares contents, duration and cost per dose side by side. Delivery is free across the UK, and subscriptions can be paused or cancelled at any time.
Frequently asked questions
Is NAD+ the same as NMN or NR?
No. NMN and NR are precursors your body has to convert into NAD+. An injection delivers the finished molecule, so nothing depends on how efficiently you convert.
Does an NAD+ injection hurt?
The micro-needles are 32-gauge and 6mm long and go into the fatty tissue under the skin, so most people feel only a light pinch. Any warmth or flushing afterwards is from the NAD+ itself, not the needle, and passes within minutes.
How long does one kit last?
A 500mg cartridge gives ten 50mg doses. A two-cartridge kit lasts about five weeks at the usual rhythm of daily for the first three days and then every other day.
Can I take NAD+ with my morning coffee?
Yes. Caffeine does not interfere with NAD+. Many people find a small breakfast first reduces any mild nausea.
How should I store NAD+?
Keep cartridges and vials in the fridge, away from light, and let the dose come to room temperature for a few minutes before injecting. Do not freeze.
Is NAD+ legal to buy in the UK?
Yes. NAD+ is a naturally occurring coenzyme, not a controlled substance, and can be bought legally for personal use. It is not a licensed medicine, so it is not intended to treat any condition, and you should involve a prescriber in your protocol.
Sources
- Massudi H et al. Age-associated changes in oxidative stress and NAD+ metabolism in human tissue. PLoS ONE, 2012.
- Clement J et al. The plasma NAD+ metabolome is dysregulated in "normal" aging. Rejuvenation Research, 2019.
- Covarrubias AJ et al. NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology, 2021.
- Martens CR et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nature Communications, 2018.
- Yoshino M et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science, 2021.
- Grant R et al. A pilot study investigating changes in the human plasma and urine NAD+ metabolome during a 6 hour intravenous infusion of NAD+. Frontiers in Aging Neuroscience, 2019.
- Braidy N, Liu Y. NAD+ therapy in age-related degenerative disorders: a benefit/risk analysis. Experimental Gerontology, 2020.
