Your diet contains small amounts of niacin -- vitamin B3 -- from food sources such as beets, peanuts, tuna, chicken and milk. Niacin in supplement form may treat conditions such as type 1 diabetes and arthritis. Doctors may also prescribe niacin to treat heart-related conditions such as high cholesterol and hardening of the arteries. All types of niacin may lower your blood pressure.
Niacin and Blood Pressure
You can purchase niacin in a 500 mg dose without a prescription. If your blood pressure is naturally low, you should not take niacin. If you suffer from hypertension -- high blood pressure -- it could prove dangerous to self-medicate with over-the-counter niacin. If you take too much niacin -- and only a doctor can determine the amount needed for your condition -- your blood pressure could drop to dangerously low levels. Over-the-counter niacin -- sometimes called no-flush niacin -- also works differently than the type of niacin prescribed by doctors.
Niacin and Niacinamide
Because high blood pressure and high cholesterol are linked -- each affects the ability of your blood to flow to and from vital organs -- you may think that purchasing niacin 500 mg will treat both conditions. But the active ingredient in over-the-counter niacin -- niacinamide -- does not help remove fat and cholesterol from your arteries. Only regular niacin helps lower cholesterol. And doctors usually prescribe it in higher doses of 1,200 mg to 3,000 mg a day.
Interactions
If you currently take other blood pressure or cholesterol medications, niacin may cause serious interactions if taken with them. If you take clonidine, a blood pressure drug, do not take niacin 500 mg without a doctor's supervision. Doctors sometimes prescribe both niacin and statins to lower cholesterol. Taking both medications at the same time could make you more susceptible to muscle damage. Niacinamide may help prevent type 1 diabetes in children or delay the need for taking insulin for persons diagnosed with the disease. But 500 mg may prove more or less than needed. A doctor can determine the correct dose and monitor for side effects such as low blood pressure.
Precautions
If you take 500 mg of any kind of niacin, you may face mild side effects such as nausea, dizziness, mouth pain and skin flushes -- a condition that makes your face and chest turn red and your skin itch, tingle or burn. Niacin taken in amounts of 500 mg can also cause serious side effects, including stomach ulcers, gout, vision loss, irregular heartbeat and liver damage. Niacin taken in amounts of 2,000 mg a day -- four times the amount in 500 mg niacin -- made persons more susceptible to strokes, according to a study by the National Institutes of Health. The NIH halted the study 18 months earlier than planned, in May 2011, because of safety concerns.
