The most common side effects of NAD+ injections are a short-lived flush of warmth, mild nausea or light-headedness, and a small bump or redness where the needle went in. They are usually mild, pass within minutes to hours, and depend on dose and speed. A smaller dose, a slower injection, something to eat beforehand and rotating sites prevent most of them.
This guide is for adults who are about to start NAD+ injections at home, or who have just had a first injection and want to know whether what they felt is normal. It covers each side effect in turn, why it happens, what reduces it, how the evidence stands, and the point at which you should stop and speak to a professional.
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. If you feel seriously unwell after an injection, call 999 or NHS 111.
NAD+ side effects at a glance
Almost everything people report after a subcutaneous NAD+ injection falls into one of three groups: a whole-body reaction while the dose is absorbed, a stomach or head reaction shortly after, and a local reaction in the skin. The table sets out what each one feels like and what to change next time.
| Side effect | What it feels like | When it starts | How long it lasts | What helps |
|---|---|---|---|---|
| Flushing | Warmth in the face, neck or chest, sometimes a feeling of pressure or tightness | Within a few minutes | Usually minutes, occasionally up to half an hour | Lower dose, slower injection, sit down and breathe normally |
| Nausea | Queasiness, an unsettled stomach, occasionally cramping | Within 5 to 20 minutes | Usually under an hour | Eat a small meal first, drink water, lower dose |
| Light-headedness or headache | A brief dizzy or heavy-headed feeling | Within minutes | Minutes to an hour | Inject sitting down, hydrate, do not inject fasted |
| Sting on injection | A sharp or burning feeling as the liquid goes in | Immediately | Seconds to a couple of minutes | Let the cartridge reach room temperature, let the skin dry after the wipe |
| Bump, redness or itch at the site | A small raised or pink patch, sometimes tender | Minutes to hours | Hours to a few days | Rotate sites, pinch the skin fold properly, hold the pen in place for ten seconds |
| Bruise | A small blue or yellow mark | Within a day | Several days | Do not rub the site, avoid visible veins, fresh needle every time |
| Feeling wired or tired | Restlessness at night, or a dip in energy later in the day | Hours later | That day | Move the injection to the morning, review the dose |
None of these is unusual in the first week, and most people have one or two of them once and then not again. If you are still at the stage of deciding whether injections are for you, the complete UK guide to NAD+ injections gives the wider picture.
The NAD+ flush: warmth, pressure and a racing feeling
The flush is the side effect people ask about most, partly because it is the most surprising. A few minutes after the injection you may feel warmth spreading across the face, neck or chest. Some people also describe a feeling of pressure in the chest or abdomen, or a sense that the heart is beating harder. It tends to peak quickly and fade within minutes.
The same reaction is well known from clinic infusions, where it is the reason NAD+ drips run over two to four hours. Staff slow the drip when a patient feels tightness or warmth, and the feeling eases. That tells you what matters: how much NAD+ arrives in the bloodstream and how fast. The exact mechanism has not been established in published research, and it is not the same thing as the niacin flush, although the two are often confused.
A subcutaneous injection has two built-in advantages here. The dose is small, 50mg rather than 250mg to 500mg, and absorption from the fat layer under the skin is gradual. That is why many people on a pen protocol never feel a flush at all, and those who do usually describe it as mild.
How to reduce it
- Start at 25mg. That is 0.15ml, or 15 clicks on the pen. Take it for the first one or two injections, then move to 50mg.
- Inject slowly. With a syringe, press the plunger over several seconds rather than in one push. With the pen, press steadily and hold for a slow count of ten.
- Sit down for five minutes afterwards. The flush passes faster when you are still and breathing normally than when you are rushing out of the door.
- Do not stack doses. If you miss a day, carry on with the usual dose. Doubling up is the quickest route to a strong flush.
Nausea, stomach discomfort and light-headedness
Nausea is the second most common complaint. It tends to arrive a little after the injection, feels like a queasy or unsettled stomach, and usually settles within the hour. Light-headedness and a mild headache belong to the same family and often travel with it.
The pattern in what customers tell us is consistent: it is more likely on an empty stomach, more likely when dehydrated, and more likely at higher doses. All three are easy to change.
- Eat first. A small breakfast twenty to thirty minutes before the injection is enough. Toast, yoghurt or a banana will do.
- Drink a glass of water before and another after.
- Inject sitting down, and stay seated for a few minutes if you tend to feel faint around needles.
- Drop back a step. If 50mg makes you queasy, return to 25mg for a week and build up again.
Injection site reactions: sting, bumps, redness and bruises
Local reactions come from the injection rather than from NAD+ circulating in the body, and technique accounts for most of them.
Sting. NAD+ solution can sting briefly as it goes in. It stings more when it is cold, and more when the alcohol from the prep wipe is still wet on the skin. Take the cartridge or vial out of the fridge about ten minutes beforehand, and let the skin dry for a few seconds after wiping. Do not warm the cartridge in water or on a radiator.
A small bump. A raised area the size of a pea is simply the liquid sitting under the skin before it disperses. It normally flattens within an hour or two. Bumps that linger usually mean the injection was too shallow, the skin fold was not pinched up, or the same spot has been used too often.
Redness or itch. A pink patch that fades the same day is a mild irritation. Redness that spreads, feels hot, or gets worse after 24 hours is different, and is covered below.
Bruising. A 32-gauge needle is very fine, but it can still nick a tiny vessel. Avoid any visible veins, do not rub the site afterwards, and never reuse a needle: a used tip is blunter and does more damage on the way in.
Rotate every time
Use the abdomen, at least five centimetres from the navel, or the outer thigh. Move to a different spot for each injection and alternate sides. Injecting the same place repeatedly causes small lumps and slows absorption. The full sequence, with the pen and with a syringe, is in how to inject NAD+ at home, step by step.
Why dose and speed matter most
If there is one idea to take from this article, it is that the systemic side effects of NAD+ follow the dose. That is the reason the reference protocol is built from small, frequent injections rather than large, occasional ones.
- Reference dose: 50mg per injection, which is 0.3ml or 30 clicks on the pen, and 25 units on a U-100 syringe with the 1000mg vial.
- Gentle start: 25mg for the first one or two injections.
- Rhythm: once a day for days 1 to 3, then every other day.
- Ceiling without a prescriber: 100mg per injection and 500mg per week.
If a dose gave you a flush or nausea that you would rather not repeat, the answer is nearly always to halve it and build up over a week or two, not to push through. The numbers for each device are laid out in the NAD+ injection dosage guide, and the dosage calculator converts any target dose into clicks for the pen or units for a syringe.
A pre-injection checklist that prevents most problems
- Eat something small and drink a glass of water.
- Take the cartridge or vial out of the fridge ten minutes beforehand.
- Wash your hands. Attach a new needle.
- Dial the dose and check it in the window before you inject.
- Choose a different site from last time. Wipe it and let it dry.
- Pinch a fold of skin, press the pen in at 90 degrees, inject, and count slowly to ten.
- Remove the needle into the sharps bin. Do not rub the site.
- Sit for a few minutes. Note the dose and how you felt, so you can adjust with evidence rather than memory.
What the evidence shows, and what it does not
It is worth being straightforward about the quality of the data.
What exists. The best human safety data for NAD+ itself comes from intravenous use. A 2019 pilot study in Frontiers in Aging Neuroscience followed a small group of healthy adults through a six-hour infusion and monitored them throughout, and a 2020 benefit and risk analysis in Experimental Gerontology concluded that NAD+ therapy appears well tolerated while calling for larger studies. Trials of the oral precursor NR, including a 2018 study in Nature Communications, also reported good tolerability in middle-aged and older adults.
What does not exist. There are no large, long-term controlled trials of self-administered subcutaneous NAD+. The side effect profile described here comes from clinic experience with infusions, from the smaller doses used under the skin, and from what our own customers report. That is useful, practical information, but it is not the same as trial data, and rare or long-term effects cannot be ruled out on that basis.
This is one reason we keep repeating the same advice: involve a prescriber, start low, and stay within the published limits.
When to stop and get medical advice
Mild, brief reactions that follow the patterns above do not normally need anything more than a lower dose next time. The following are different.
Call 999 straight away if, after an injection, you have swelling of the lips, tongue, face or throat, difficulty breathing, a widespread rash or hives, or you feel faint and clammy. These are signs of a serious allergic reaction.
Stop injecting and contact your GP, prescriber or NHS 111 if you have:
- Chest pain, palpitations or breathlessness that do not settle within a few minutes of resting.
- Redness at the site that spreads, feels hot, becomes more painful after 24 hours, or produces pus, with or without a fever. These can be signs of infection.
- Vomiting, a severe headache, or dizziness that persists.
- The same side effect returning at 25mg after you have corrected technique, food and hydration.
Do not inject a solution that looks cloudy, discoloured or has particles in it, and do not use a cartridge or vial that has been left out of the fridge for an extended period. If in doubt, ask us before using it.
Who should not use NAD+ without medical advice
NAD+ injections are for adults only. Do not start without speaking to a doctor or prescriber 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. If you take regular medication of any kind, check with your prescriber first.
Starting gently: which kit makes it easiest
If your main concern is how you will tolerate NAD+, a pen is the simpler route. The dose is dialled rather than drawn up, the needle is shielded, and stepping from 25mg to 50mg is a matter of turning the dial.
- To test how you respond: the NAD+ Trial Kit includes the pen and one 500mg cartridge, which is ten 50mg doses or twenty at 25mg.
- To run a full first month: the NAD+ Discovery Kit includes the pen and two 500mg cartridges, roughly five weeks of protocol.
- Running low on needles: 32G micro-needles are available separately, so there is never a reason to reuse one.
Every kit includes needles, prep wipes, a sharps bin and a quick-start guide. Delivery is free across the UK. You can see the full range in the NAD+ collection.
Frequently asked questions
What are the most common side effects of NAD+ injections?
A brief flush of warmth in the face or chest, mild nausea or light-headedness, and a small bump, redness or bruise at the injection site. They are usually mild and pass within minutes to hours. Most are reduced by a lower dose, a slower injection, eating beforehand and rotating sites.
How long does the NAD+ flush last?
For most people it peaks within a few minutes of the injection and fades within minutes, occasionally up to half an hour. If it is strong or lasts longer, use a smaller dose next time. Chest pain or palpitations that do not settle with rest need medical advice.
Why do I feel sick after an NAD+ injection?
Nausea is linked to the dose and is more likely on an empty stomach or when you are dehydrated. Eat a small meal twenty to thirty minutes beforehand, drink water, and drop to 25mg for a week before building back up to 50mg.
Is a lump at the injection site normal?
A small raised bump that flattens within an hour or two is the liquid dispersing under the skin and is normal. Rotate sites and pinch the skin fold properly to avoid it. A lump that becomes hot, red, more painful or produces pus should be checked by a GP or NHS 111.
Do NAD+ side effects go away over time?
Many people notice a flush or queasiness with the first few injections and less or nothing afterwards, particularly once dose and routine are settled. If a side effect keeps returning at 25mg with good technique, stop and speak to a prescriber.
Can NAD+ injections affect sleep?
Some people report feeling more alert for a few hours after a dose. If you find it harder to fall asleep on injection days, move the injection to the morning.
Sources
- 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.
- Martens CR et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nature Communications, 2018.
- Covarrubias AJ et al. NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology, 2021.
