Is Too Much Niacin Bad for You?

Too much niacin can have bad side effects.
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Niacin is an essential nutrient, but is there such a thing as too much niacin? Here's what you need to know about this nutrient, the recommended intake and the effects of consuming too much niacin.



Taking high doses of niacin via supplements can cause serious side effects, ranging from flushed skin and gastrointestinal issues to liver damage and diabetes.

Importance of Niacin

The University of Rochester notes that niacin is part of the B complex group of vitamins. According to the Harvard T.H. Chan School of Public Health, there are collectively eight B vitamins, of which niacin is vitamin B3.

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Read more: The Surprising Benefits and Side Effects of B-Complex Vitamins


The Mayo Clinic explains that your body uses niacin to turn the food you eat into energy. It basically helps your body use the carbohydrates, fats and proteins that you consume. In fact, the University of Rochester says that niacin is involved in two enzyme systems within your body; these systems affect every single one of your tissues.

The Mayo Clinic adds that niacin helps keep your digestive system and your skin healthy. A February 2019 study published in the International Journal of Molecular Sciences notes that niacin is also vital to the healthy functioning of your nervous system.


According to a study published in the February 2012 issue of the journal Current Atherosclerosis Reports, niacin is also prescribed to help regulate cholesterol levels.

The University of Rochester explains that while your liver uses the amino acid tryptophan to make niacin, your body can also absorb the niacin in food. This nutrient is found in many foods like yeast, meats (liver especially), seeds, grains and legumes. Niacin is also found in many enriched foods, like corn tortillas, for example. You can get niacin through multivitamin and multimineral supplements and niacin supplements as well.


The National Institutes of Health (NIH) recommends that adult males get 16 milligrams of niacin a day and that adult females get 14 milligrams. Pregnant women require 18 milligrams of niacin per day and lactating women require 17 milligrams.

The Mayo Clinic notes that most people are able to satisfy their niacin requirements through the food they eat. In fact, niacin deficiencies, known as pellagra, are uncommon in the United States.



According to the University of Rochester, niacin is a water-soluble vitamin, which means that any excess is flushed out of your system by your kidneys. As a result, the NIH states that most people can tolerate up to 35 milligrams of niacin per day.

Read more: What Are the Pros and Cons of Taking 500 mg of Niacin?

Effects of Too Much Niacin

Per the NIH, the problem of too much niacin can arise if you are taking supplements that deliver a niacin dosage of over 30 milligrams. It's worth noting that some cholesterol patients are prescribed a niacin dosage that is over 1,000 milligrams, so the side effects can be pretty serious.


The Mayo Clinic lists some of the side effects caused by high doses of niacin, taken via supplements:

  • Flushed skin
  • Dizziness
  • Itching
  • Rapid heartbeat
  • Diarrhea
  • Abdominal pain
  • Nausea
  • Vomiting
  • Liver damage
  • Gout
  • Diabetes

If you suspect that you have overdosed on niacin, you should seek medical help immediately. You should also discuss any existing conditions you have with your doctor before you start taking niacin supplements. According to the Mayo Clinic, niacin supplements can exacerbate certain health issues like allergies, gallbladder conditions and certain thyroid disorders.


The Mayo Clinic also recommends that people with certain conditions avoid taking niacin or take it cautiously and only under medical supervision. These conditions include low blood pressure, liver disease, peptic ulcer disease, gout and diabetes.

The Mayo Clinic states that it is safe for pregnant and lactating women to take niacin to correct a niacin deficiency; however it is not safe for them to take niacin supplements to treat cholesterol.


Per the Mayo Clinic, it's also possible that niacin supplements may interact with certain medications and substances, like alcohol, statins, zinc, chromium, anticoagulant and antiplatelet drugs, hepatotoxic treatments, and medications for diabetes, blood pressure and gout.

Read more: What to Do if You Have a Niacin Reaction




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