Quick answer

Yes. NIH says 30 to 50 mg or more of nicotinic acid typically causes flushing, a reddening of the face, arms and chest with burning, tingling and itching. The label of a prescription niacin tablet says up to 88% of patients had flushing in trials. Nicotinamide does not cause flushing. Ask your doctor if flushing is severe.^1,2

Key facts

NIH says 30 to 50 mg or more of nicotinic acid typically causes flushing, with burning, tingling and itching of reddened skin on the face, arms and chest.¹
In trials of a prescription niacin tablet, flushing was reported by as many as 88% of patients, and 6% stopped the tablets because of it.²
NIH describes flushing as unpleasant rather than toxic, and says it can come with headache, rash, dizziness or a drop in blood pressure.¹
Nicotinamide, also called niacinamide, does not cause flushing.¹
Tolerance to flushing builds over several weeks, and flushing is most likely when starting niacin or raising the amount.^1,2

What does niacin flushing look and feel like?

NIH says that 30 to 50 mg or more of nicotinic acid typically causes the skin of the face, arms and chest to turn reddish because small blood vessels under the skin widen. It comes with burning, tingling and itching, and it can start within 30 minutes of a dose or build over days or weeks of repeated dosing.¹

Nicotinic acid at 30 to 50 mg or more often causes flushing: the skin of the face, arms and chest turns red and can burn, tingle and itch. It usually passes and is considered unpleasant rather than toxic.^1,3

Flushing can come with headache, rash, dizziness or a drop in blood pressure.^1,3

How common is niacin flushing in trials?

The prescription niacin label answers with numbers. In placebo-controlled trials of the extended-release tablet, flushing episodes with warmth, redness, itching or tingling were reported by as many as 88% of patients, making them the most common adverse reaction. Flushing led 6% of patients to discontinue treatment, against none on placebo in the label's adverse-reaction table.²

The label adds that flushing can come with dizziness, a fast heartbeat, palpitations, shortness of breath, sweating, chills or swelling, and that in rare cases it leads to fainting. It says it is most likely at the start or when the amount is raised, and that tolerance develops rapidly over several weeks.²

Which forms of niacin cause flushing?

Flushing comes from nicotinic acid, which is also the form in prescription niacin. NIH says nicotinamide does not cause flushing because of its slightly different structure, and that some nicotinic acid products are labeled prolonged, sustained or extended release to lessen it.¹

Inositol hexanicotinate is often labeled as flush free. NIH says it does not cause flushing, but that on average about 30% less niacin is absorbed from it, so a flush-free label is a statement about flushing and not about the rest of a product's effects.¹

Nicotinamide does not flush, but at 500 mg a day or more it can cause diarrhea and easy bruising and can increase bleeding from wounds. At 3,000 mg a day or more it can cause nausea, vomiting and liver damage.^1,3

What makes flushing stronger or milder?

NIH says supplement users can reduce flushing by taking nicotinic acid with food, raising the amount slowly or waiting for the body to build tolerance. The prescription label and MedlinePlus add that alcohol, hot drinks and spicy foods around the time of a dose can make flushing and itching worse.^1,2,4

Those points describe what the sources report, not a plan for any one person. Anyone using prescription niacin should follow the prescriber's directions and ask the pharmacist before adding aspirin or any other product to ease flushing.^2,4

When is it more than flushing?

NIH lists more serious effects at much higher amounts of nicotinic acid, from 1,000 mg a day or more: low blood pressure that raises the risk of falls, high blood sugar, nausea, stomach pain and blurred vision. It also says high doses taken for months or years can harm the liver, more so with extended-release forms.¹

High doses of nicotinic acid taken for months or years can harm the liver, from raised liver enzymes to hepatitis and liver failure. This is more likely with extended-release forms, and severe cases have followed switching from immediate-release to sustained-release niacin at the same dose.^1,2

The prescription leaflet warns that heart attack symptoms can differ from a flushing reaction. It lists chest pain, pain in the arm, back, neck, jaw or stomach, shortness of breath, sweating, nausea and lightheadedness, and says to call a doctor right away if they occur.²

Who should ask a doctor or pharmacist about niacin flushing?

Anyone whose flushing is severe, keeps coming back or comes with dizziness, fainting, a fast heartbeat or breathing trouble.^1,2
Anyone who takes prescription niacin, since the label has specific directions on timing and on avoiding certain drinks and foods.²
Anyone who takes a blood pressure medicine, since flushing can come with a drop in blood pressure.^1,2
Anyone considering a flush-free product, to compare how much niacin it actually supplies.¹

Questions people ask

Does niacin cause flushing?

Yes, nicotinic acid does. NIH says 30 to 50 mg or more typically causes redness, burning, tingling and itching of the skin, and a prescription niacin label reports flushing in as many as 88% of trial patients. Ask your doctor if it is severe.^1,2

Does niacin cause itching?

Itching often comes with flushing. NIH says flushing is accompanied by burning, tingling and itching, and the prescription label lists pruritus among its most common reactions.^1,2

Does niacin cause hot flashes?

The prescription label describes flushing as warmth, redness, itching or tingling of the skin, and MedlinePlus places it on the face, neck, chest or back. The sources checked do not compare it with hot flashes from other causes, so ask your doctor.^2,4

Does niacinamide cause flushing?

NIH says nicotinamide, also called niacinamide, does not cause flushing, though it has its own effects at much higher amounts, including nausea, vomiting and liver damage at 3,000 mg a day.¹

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure line

Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.