niacin flush symptoms

Niacin Flush: What to Know

Last modified on February 14th, 2023

I recently heard a term that I was unfamiliar with—niacin flush. I came across the term in the context of niacin potentially having beneficial effects for people with COVID symptoms and long COVID. I decided to do some research on my own about the benefits of niacin in general, how this could relate to COVID-19, and what exactly is meant by the term flush.

Below, I cover everything you need to know about niacin, which I’m increasingly learning is one of the most essential nutrients that many of us may be deficient in.

niacin flush benefits, no flush niacin, what is niacin flush

What is Niacin?

Niacin is a B vitamin. Your body uses it to turn your food into energy. This B vitamin plays a role in the health of your nervous and digestive systems, as well as the health of your skin. Also known as B3, you can get niacin from cereal grains, yeast, milk, and meat. B3 is also available in prescription form as medicines like Niacor and Niaspan, which control cholesterol and lower cholesterol levels. 

The daily recommended intake of niacin for adult males is 16 mg. For women, it’s 14 mg, but many researchers believe we should get much more than this for optimal health.

As a supplement, niacin has the potential not only to lower cholesterol and have positive effects on lipid levels but improve your brain function and reduce symptoms of arthritis. There are risks of taking too much, however, which we talk about below.

Types of Niacin

There are two chemical forms of niacin, which is one of eight B vitamins. There is nicotinic acid. As a supplement, nicotinic acid is used to lower cholesterol and reduce the risk of heart disease.

There’s also another type called niacinamide or nicotinamide, which doesn’t lower cholesterol but may help with skin conditions like psoriasis. Niacinamide may reduce the risk of non-melanoma skin cancer.

Niacin is water-soluble, meaning your body can’t store it. When you don’t need it, your body will get rid of the excess.

As is the case with other B vitamins, B3 converts food into energy by helping your enzymes.

Here’s a big thing to note about it—it’s a component of NAD and NADP, which we’re going to talk about more. B3 also plays a valuable role in making and repairing DNA, and it’s an antioxidant.

What Is NAD?

The most significant benefit of niacin as a supplement in the eyes of many doctors and researchers is its ability to help you produce NAD.

NAD is nicotinamide adenine dinucleotide. NAD is the most critical molecule in cellular metabolism. Without NAD+, we would die in 30 seconds. NAD helps the function of your mitochondria, and it allows your cells to generate. NAD+ helps your body maintain its DNA integrity and promotes a better immune system.

NAD can also help protect you from some of the effects of disease and aging.

NAD+ works by transferring electrons across your molecules. It works along with NADH to facilitate metabolic exchanges. These metabolic reactions, generated by NAD and NADH, generate ATP, your body’s energy molecule. If you don’t have enough AND, you may not, in turn, produce enough ATP.

NAD also repairs damaged DNA, regulates your sleep/wake cycle, and helps you maintain stability in your chromosomes.

As we age, our NAD+ levels fall. DNA damage accumulates, and that then activates something called PARP. PARP is an enzyme that uses NAD+ to repair your DNA function. PARP breaks down NAD+ as part of this process.

The depletion of NAD+ through PARP activation has an association with the development of a variety of diseases. NAD+ depletion because of PARP may lead to DNA damage itself, as well as an inflammatory state linked to many diseases.

Our immune systems have enzymes that require NAD+ too. The more active your immune system, the more NAD+ consumption.

Our bodies make NAD+ through a process called biosynthesis. Two pathways provide biosynthesis. One is called the de novo path, and the other is the salvage pathway.

Tryptophan, an essential amino acid, is the beginning of the de novo pathway. Tryptophan comes from food sources like meat and fish. The conversion to NAD+ happens in a particular part of our cells, the cytosol.

The salvage pathway of NAD biosynthesis uses vitamins including nicotinamide, nicotinic acid, something called nicotinamide mononucleotide or NMN, and nicotinamide riboside or NR.

All this can get complex, but the big things to know are:

  • When your NAD+ levels are reduced or disturbed, it can cause problems with metabolism, leading to insulin resistance. Not only aging but also obesity disturb your NAD+ levels.
  • Metabolic disorders caused by low NAD create a cascade effect. For example, metabolic disorders and declines in NAD can lead to high blood pressure. The increased blood pressure can then cause heart function to decline. Then, damaging waves can be sent to the brain, causing cognitive impairment.
  • Targeting NAD+ is an integral part of protecting yourself against metabolic dysfunction and diseases related to aging. Research suggests lower NAD+ levels that come with aging can lead to the onset of age-related disorders and diseases.
  • When your NAD+ levels go down, you may have a reduction in your DNA repair, the regulation of your energy metabolism, and problems with your cellular stress response.
  • By the time you’re 50, you have around half the NAD+ that you did when you were 20.
  • Age-related diseases include not only metabolic disorders but heart disease and neurodegeneration.
  • When you find ways to replenish your NAD+ levels, you can reverse signs of aging and lower your likelihood of developing age-related disorders.
  • Animal research is starting to show that if you’re able to increase your NAD+ with supplementation, it could have a modest effect on extending your lifespan.

There are various ways to increase your body’s levels of NAD+, such as intermittent fasting or NAD supplement.

Perhaps even better than that, however, is the use of niacin. In human trials, researchers are finding that niacin has the potential to increase NAD+ significantly.

In one specific human trial, participants got a steadily increasing dose of niacin. They started with a dose of 250 mg a day. Then, over four months, that increased to 750 to 1000 mg a day. Then, there was a follow-up protocol at ten months.

Niacin supplement increased muscle NAD+ levels by 1.3x at four months and 2.3x at ten months in the study group.

The level of whole blood NAD+ was 7.1x greater in the study group and 5.7x greater in the control group after four months compared to the baseline. This went up to 8.2x by ten months.

We should note that the control group was healthy individuals. The study group was people with mitochondrial myopathy. All participants did the same regime of niacin supplementation. Results showed that niacin supplementation might significantly affect deficient people rather than healthy people who already have optimal levels.

NAD+ may prove to be one of the most important things going forward in research on anti-aging, DNA repair, and the prevention of metabolic and aging-related diseases.

What Causes Niacin Flush

NAD+ and COVID-19

We want to emphasize that we’re only presenting research as it currently exists as far as NAD+ and the action of niacin and their potential benefits for COVID-19. This is not medical advice.

However, researchers are increasingly theorizing that increasing levels of NAD+ can improve immune function in COVID-19 function. Much of this has to do with what we talked about early—NAD+ levels go down as we age.

Lower NAD+ associated with aging can negatively affect your body’s immune response to any infection, including COVID-19. There is evidence of age-related dysfunction of the immune system, which is the death rate among older people who are infected is so much higher overall than young people.

While there’s a lot we don’t know, it’s possible that restoring NAD+ levels could reduce your immune reaction and improve your condition if you have COVID-19. Again, much more research is needed, but DNA differences exist between younger and older people that can influence our immune response.

NAD+ also plays an essential role in your antiviral response. When there’s an excessive PARP activation and an inflammatory response to SARs-CoV2, it can cause excessive consumption of NAD+, reducing cellular levels even more. Then, that can cause cell depletion and death.

Some researchers suggest using NAD+ as an immunomodulator for older patients to decrease the severe immune reaction of the virus. Niacin can also help, as we discussed, to raise NAD+ levels.

Does this mean that niacin is a cure for COVID-19? Absolutely not, but it does show an exciting area of research now and going forward.

In general, vitamin B deficiency can impair the immune system function and lead to inflammation. B vitamins help the innate and adaptive immune response and can reduce cytokine levels while improving respiratory function. Many researchers are calling on doctors to assess vitamin B status in COVID-19 patients.

We found one research study that showed as a building block of NAD and NADP, niacin could potentially play a much bigger role in how we deal with viral infections. NAD+, as we touched on, is released during the early stages of inflammation. NAD+ has immunomodulatory properties that can reduce inflammatory cytokines.

Niacin may also help reduce the infiltration of neutrophils, and it can have an anti-inflammatory effect in patients with lung injury from ventilators. In animals, niacin prevents damage to lung tissue. Nicotinamide reduces viral replication.

We linked all the references below so you can take a look yourself.

how long does niacin flush last

Health Benefits of Vitamin B3 

Along with the fact that niacin is a precursor to NAD+ and NADH and plays a role in modulating the immune system, reducing inflammation, and combatting aging-related diseases, this B vitamin has other health benefits.

Lowers Cholesterol

One of the main reasons people take niacin supplements is to lower cholesterol. Since the 1950s, we’ve been using niacin because of its beneficial lipid effects and ability to lower triglyceride levels. Niacin isn’t the first-line treatment, though. Instead, it’s used if you can’t take a statin for any reason.

Along with lowering bad LDL cholesterol levels, niacin effects on cholesterol also include raising your good HDL levels. 

Lower Risk of Heart Disease

We’ve known for a while that niacin can help lower the risk of heart disease. The primary reason that was thought to be the case is that it lowers cholesterol. Now, we’re learning B3 might have other heart benefits.

Since vitamin B3 can lower inflammation and oxidative stress, it might prevent atherosclerosis. Atherosclerosis is the hardening of the arteries contributing to heart disease.

Type 1 Diabetes

Type 1 diabetes is an autoimmune disease. If you have Type 1 diabetes, your body attacks your pancreatic cells that make insulin. Research show niacin might protect the cells and lower the possibility of developing this disorder in children at risk.

Improve Brain Function

How niacin can benefit brain function goes back to what we mention above with NAD+ and NADP. Your brain requires NAD and NADP for energy and functionality.

Niacin may help promote brain health, particularly as it relates to aging.

Some psychiatric symptoms and brain fog are associated with a niacin deficiency. Many people with long COVID report brain-related symptoms and fog and anecdotally find some relief when they start supplementing with niacin.

Skin Health

Many people find that when they use niacin, especially the kind that causes flushing, it improves the appearance of their skin. Niacin can protect your skin from sun damage, and new research shows it might also help with some types of skin cancer.

For example, there was a study where participants took 500 mg of nicotinamide, which is a form of niacin, twice a day. The supplementation reduced non-melanoma skin cancer rates among people who were at high risk.


A preliminary study found niacin helped reduce osteoarthritis symptoms and improved joint mobility. In the same study, niacin reduced the need for NSAIDs.


There is some interesting research coming out about the ability of niacin to help with symptoms of depression.

People with depression report regularly taking a B3 supplement helps reduce their feelings of sadness or hopelessness. For others they describe it as a miracle that helped their depression go away entirely.

We don’t fully understand why this might be the case. It could be due to depression’s links with vitamin B deficiency.

Some of the most common side effects of niacin deficiency include depression, apathy, anxiety,  headache and fatigue.

The two brain chemicals involved primarily with depression are serotonin and dopamine. These are mood-regulating neurotransmitters. If you have a serotonin deficiency, it can cause depression.

Serotonin is created by tryptophan, an amino acid. Niacin is part of the process where serotonin is formed from tryptophan, directly linking the vitamin and depression.

niacin flush, niacin flush benefits

Risks of Niacin Supplements

As with anything, talk to your health care provider before you take a niacin supplement. Niacin is generally a safe supplement, but the FDA doesn’t regulate it or any other supplement for that matter.

You could experience side effects including nausea, vomiting, and liver toxicity, if you take too much niacin.

The flush is a harmless side effect, which we’ll talk about more below.

Details about possible side effects aside from the flush effect include:

  • You could experience stomach irritation, nausea, or vomiting, especially if you take slow-release nicotinic acid.
  • Long-term niacin treatment has the risk of liver damage. This risk comes primarily from slow-release nicotinic acid, but in rare cases, could come from the immediate-release form of the supplement.
  • Be careful about taking large amounts of niacin (3 to 9 grams a day) because this could impact your blood sugar levels. The potentially harmful levels tend to be much higher than the recommended niacin dose even as a supplement. 
  • You may see that if you take high doses, supplement niacin could increase your body’s uric acid levels.

Vitamin B3 can interact with certain medicines, including:

  • Tetracycline: Avoid taking niacin at the same time as tetracycline, an antibiotic. Niacin can interfere with the effectiveness of this antibiotic. All B-complex supplements have similar effects.
  • Anti-seizure medicines: Certain anti-seizure medicines can cause niacin deficiency, but then taking it with medication like Mysoline or carbamazepine can increase the levels of the drugs in the body.
  • Blood thinners: If you’re on anticoagulants, niacin can increase the effects, raising the risk of bleeding.

Types of Niacin Supplements

If you’re considering supplementing with niacin, three main types are available over the counter.

These are:

  • Nicotinic acid
  • Nicotinamide
  • Inositol hexanicotinate (flush-free niacin)

Nicotinic acid and nicotinamide are the two most common types of supplemental niacin.

Nicotinic acid content causes skin flushing, so we sometimes hear this referred to as the flush.

What is Niacin Flush?

One of the most common side effects of vitamin B3 is the flush. It’s not very comfortable, but it’s also not harmful. When you take B3, especially at a high dose, your skin may feel flushed and red. You may also feel tingling, pins, and needles, and it can feel somewhat like a bad sunburn. Some people feel itchiness too.

As we mentioned, nicotinic acid is the specific type of niacin causing the flush.

Niacinamide doesn’t produce flushing, but it’s not as effective at providing health benefits. For example, niacinamide isn’t as effective at reducing cholesterol and other blood fats compared to nicotinic acid.

Nicotinic acid or flush niacin is available in an immediate-release version and extended-release.

With immediate release, the total dose is absorbed at one time, and with extended release, there’s a coating so your body absorbs it more slowly.

You’re more likely to experience flush with the immediate-release version of the supplement. At least half of everyone who takes an immediate-release version of the vitamin will experience the flushing sensation.

Specific symptoms of the flush are:

  • Reddening of the skin primarily affecting your face and upper body
  • Symptoms similar to sunburn
  • Tingling
  • Itching
  • Burning or prickly heat 
  • The skin may feel warm to the touch

Most people will experience symptoms of niacin flush around 15 to 30 minutes after taking a high dose of the supplement.

What Causes Niacin Flush?

When you take a high dose, your capillaries expand. That expansion increases blood flow to the surface of your skin.

The theory is that if you aren’t getting the niacin flush, then maybe you’re not getting the full benefits of taking it in supplement form. When you get the flush, your body is flushed with the vitamin for the most positive effects. 

Niacin Flush Benefits

Some of the potential flush benefits that explain why people are willing to endure the discomfort include:

  • May reduce bad cholesterol and increase good levels
  • Helps with the hardening of the arteries. Studies show niacin may help reduce atherosclerosis and prevent vascular inflammation.
  • There’s a detoxifying effect with the flush, which is why you might see people talking about searching for a niacin flush drug test. If someone wanted to quickly detox from drugs or alcohol they might take high-dose niacin, which could help break down the drug metabolites faster.
  • There’s some evidence that the niacin flush can help remove toxins stored in your fat cells and break fat down.
  • Pellagra is a rare condition that comes from being deficient in vitamin B3. It occurs in alcoholics and people with HIV/AIDs primarily, but high-dose niacin is a treatment.
  • Some people feel flushing niacin, in general, makes their skin healthier and more glowing, maybe because of the way it draws blood to the surface temporarily.

If you’re taking vitamin B3 because you want to reduce inflammation, increase NAD+, or reduce your risk of viral infections, taking the flush version is recommended. Again, no flush niacin won’t have the same health benefits.

Niacin Flush Free 

No flush niacin contains inositol nicotinate. While it doesn’t create visible flushing, it may not have as many health benefits.

Is the Niacin Flush Reaction Dangerous?

Flushing from niacin is not dangerous in and of itself. Most people find that after taking niacin for a few days, the flushing effect starts to go down. You can also take it on a full stomach or with a lot of water, and the flush effects should be less dramatic. Taking it with low-dose aspirin may also help.

Eating an apple before you take niacin seems to be an effective way to make the flush less intense, but you’ll still get the positive health effects. 

While the flush itself isn’t dangerous, high doses of this vitamin can be harmful. There are rare but severe side effects such as liver damage if you take too much. You should talk to your doctor before you take any supplements.

Also, avoid high doses of niacin if you’re pregnant because it’s a category C drug, meaning it could lead to birth defects. 

Many people worry that the flush is an allergic reaction, which it’s not. 

What is the Best Flush Niacin?

Our top picks for the best types of niacin to produce a flush are detailed below.

Nutricost Niacin 500 mg

I personally use this type of flushing Niacin as an immune system booster. I get a pretty strong flush with this product, especially if I take it on an empty stomach, but the response has gotten weaker with regular use.

I like this product because it’s inexpensive, and you get 240 capsules. Taking only one a day, these will last you for quite some time.

It’s a 500 mg dose, so you may find that’s too strong for you, in which case you might start more slowly.

Nutricost Niacin

BlueBonnet Niacin 100 mg

This BlueBonnet product is very affordable, and each capsule is only 100 mg of flushing niacin. This is good if you want to start with a lower dose and build up gradually as you’re able. It’s highly rated by users, and since the amount is lower, the flush effect isn’t likely to be as overwhelming as it would be with a higher dose.

niacin flush, what causes niacin flush

Seeking Health Niacin

It’s hard, in our opinion to go wrong with the Seeking Health brand. We’re big fans. This niacin is flushing and each capsule is only 50 mg, so it’s even better if you want the flush, but you don’t want too much discomfort. You can gradually build up your dose as you feel comfortable doing so.

Users say this product helps them in various ways, including to help with anxiety and depression.

If you have methylation problems, you might also want to give this a try.

what is niacin flush, how long does niacin flush last

Final Thoughts

I have done a lot of research recently about vitamin B3, and especially flush niacin. I feel like it’s potentially one of the more important supplements right now because of its role in producing NAD+. As we unlock more information about NAD+ and its role in everything from COVID to aging, I think facilitating its production will become one of the big priorities in natural health.

It also seems flush niacin has some other pretty incredible benefits, including potentially helping with symptoms of depression.

With that being said, high doses of niacin therapy can cause uncomfortable side effects, including the flush response.

Taking high doses of niacin can lead to serious side effects or interactions with medications you take, especially extended-release niacin compared to immediate-release niacin. Don’t take it if you have liver disease or gallbladder disease. Talk to your doctor if you have cardiovascular disease including coronary heart disease. 

I encourage you to look into niacin supplements, but speak to your health care provider and get medical supervision before taking anything, especially if you have existing health conditions or take any medications.

1 thought on “Niacin Flush: What to Know”

  1. Pingback: Sovereign Silver Review: What to Know - The Top Supplements

Leave a Comment

Your email address will not be published. Required fields are marked *

Subscribe For News and Updates on Health, Wellness, Vitamins and Supplements