Niacin flush may occur after taking large supplemental doses of niacin (vitamin B3). This vitamin is often used to treat high cholesterol levels. While uncomfortable, the warm, itchy, red skin is not dangerous.
This article reviews symptoms of niacin flush, how long symptoms last, and guidance to minimize skin flushing.
High doses of supplemental niacin in the form of nicotinic acid bring about a reaction that causes the expansion of your capillaries. Capillaries are the smallest blood vessels that form a connection between the smallest arteries with the smallest veins. This expansion increases blood flow to the surface of the skin.
When blood flow increases on the skin’s surface, symptoms of flushing can occur, including:
- Reddening of the skin
- Itchy skin
- Tingling or burning sensation
- Skin that’s warm to the touch
Niacin skin flushing usually occurs within 30 minutes of taking supplemental niacin and tends to affect the face, neck, or upper chest.
While niacin flush can happen to anyone, people with darker skin tones may not experience reddening of the skin. Instead, the affected area may be discolored or darker than the rest of the skin.
Niacin flush is not harmful, though it may be unpleasant. It generally lasts just a short time.
Talk with a healthcare provider If you experience additional symptoms, such as dizziness, a drop in blood pressure, fatigue, nausea, heartburn, or blurred vision.
Stop taking high-dose niacin supplements if you are pregnant, and discuss appropriate supplements with a healthcare provider.
A niacin flush will usually last for 30 to 90 minutes. Flushing tends to be less severe and may decrease after continuous use of nicotinic acid supplements.
Flushing usually occurs after taking 30 to 50 milligrams (mg) or more of nicotinic acid.
When taken in higher doses of 1,000 to 3,000 mg per day, nicotinic acid can also cause more serious adverse effects.
