The answer has to do with one of niacin’s most noticeable effects.
A sufficiently high dose of nicotinic acid, one form of vitamin B3, can cause what’s known as a niacin flush.
The skin may become warm, red, itchy, or tingling, particularly on the face, neck, chest, and arms.
This happens partly because blood vessels near the skin’s surface widen.
For some people, the sensation can be surprisingly intense.
You might suddenly feel:
- Warmth
- Facial flushing
- Tingling
- Itching
- Skin redness
- A temporary feeling of increased blood flow
This is probably why online posts sometimes describe niacin as a vitamin that “opens the blood vessels.”
However, that description can be misleading.
Niacin Is Not a Miracle Cure for Poor Circulation
A temporary flushing response is not the same thing as treating an underlying circulation problem.
Poor circulation can have many different causes, including peripheral artery disease, diabetes, smoking, high blood pressure, high cholesterol, blood clots, and other medical conditions.
Taking niacin without knowing the cause of circulation problems may therefore delay appropriate treatment.
If someone regularly experiences cold feet, leg pain while walking, numbness, swelling, skin color changes, or wounds that heal slowly, those symptoms deserve medical attention rather than simply being treated with a vitamin supplement.
