Also known as vitamin B3, niacin plays a very important part in a healthy diet. It aids in digestion, helps create hormones, promotes healthy skin and hair, converts food to energy, and ensures proper nerve function. When there is too little niacin in the diet, problems happen, such as vomiting, fatigue, diarrhea, indigestion, dry and cracked skin, a bright red and swollen tongue, canker sores, depression, forgetfulness, and a burning sensation in the mouth. Niacin can be found in numerous foods, including meat, fish, eggs, yeast, grains, green veggies, beans and dairy. It can also be taken in multivitamin supplements. However, just as too little niacin is a problem, so is having too much of it in your diet.

How Much Niacin Is Too Much?

Though your body definitely needs niacin, too much of it can actually be toxic. Adults should not exceed 35 milligrams in a day. Teenagers up to the age of 18 can tolerate 30 milligrams at most per day, while those between the ages of 9 and 13 shouldn’t have more than 20 milligrams per day. Most people get enough niacin in their diet and do not need a supplement; only those who have a true niacin deficiency, as diagnosed by a physician, should consider taking niacin supplements.

To help you understand the standard of taking too much niacin, here is a table explaining the exact RDA for each age group.

What Are the Side Effects of Eating Too Much Niacin?

After the answer to “how much niacin is too much?” you also need to know the possible side effects of eating too much niacin. Excess niacin can do harm to the following organs or systems.

• Skin and hair. Too much niacin can lead to terrible side effects, including the loss of your hair, cracked and dry skin, rashes, skin flushing, and severe itching. 
• Liver. Your liver has trouble handling high doses of niacin, and that could lead to jaundice, increased blood liver enzymes, severe liver damage and even liver failure.
• Heart and blood. Too much niacin can lead to circulatory collapse, palpitations, abnormal heart rhythms, reduced white blood cell count, excess clotting, and the potential for long-term heart disease.
• Digestive system and stomach. Nausea, vomiting, diarrhea and abdominal pain are common with excess niacin intake. You might also experience constipation, loss of appetite and weight loss.
• Muscles and joints. Muscle cell damage, weakened muscles, muscle pain and joint pain are common problems for those who take too much niacin.
• Nervous system. Niacin toxicity can make you confused, irritable and very tired. You might faint, suffer from headaches, undergo mental changes and even have seizures.
• Bladder and kidney. Producing higher quantities of urine, urinating frequently and having cloudy urine are all side effects of too much niacin. You might also suffer from poor kidney and bladder function.

How to Treat Niacin Overdose

Knowing “how much niacin is too much” can help you determine whether you have taken too much. If you believe you are getting excess niacin or you experience side effects, speak to your doctor.

If you have overdosed on supplements, seek medical help immediately. At the emergency department, certain medications might help, or gastric lavage might be used to rid the stomach of any supplements left there. Severe overdoses require careful monitoring to ensure no heart problems and other dangerous issues.

Precautions of Taking Niacin Supplements

If your doctor does recommend niacin supplements, keep the following in mind. If there are any doubts about the niacin dosage, be sure to double-check with your doctor on “how much niacin is too much”.

• Taking an aspirin 30 minutes before the niacin dose might help the side effects of “flush” – red skin and a burning, tingling sensation of the face and chest. 
• Alert your doctor if you have a history of diabetes or gallbladder problems. People with stomach ulcers, liver disease or kidney disease should not take niacin supplements.
• Never take niacin within two weeks of a schedule surgery.
• Remember that niacin increases histamine, which can make allergies worse.
• Taking any B vitamin, such as niacin, for a long period of time can lead to an imbalance among the B vitamins in your body. Therefore, it might be best to take a B-complex vitamin to ensure no imbalances occur.
• Due to the risk of heart rhythm changes, those who have unstable angina or coronary artery disease should never take niacin supplements without the doctor’s permission.
• Niacin can lead to drops in blood pressure. Anyone who has a history of low blood pressure should be carefully monitored while on niacin.
• Those who have a history of gout should never take niacin.