Do not take niacin and pyridoxine -- vitamins B-3 and B-6 -- without your doctor's consent and supervision. Both may turn toxic and cause serious side effects if taken in large doses. The side effects, technically not allergic reactions, may require emergency room treatment. At least one user of high doses of niacin required a liver transplant.
Prescription-strength Niacin
Doctors prescribe niacin to treat high cholesterol. Doses of up to 3,000 mg -- more than 180 times the recommended daily allowance of 14 mg to 16 mg -- prove effective in improving three types of lipids in your bloodstream: low-density lipoprotein, also known as LDL or "bad" cholesterol; high-density lipoprotein, the "good" cholesterol that helps protect you from cardiovascular disease; and triglycerides, a harmful type of fat. If you take niacin in doses of more than 100 mg daily, side effects include nausea, vomiting, headaches and skin flushes -- your face and chest may burn, itch, tingle and turn red. Niacin may worsen symptoms of kidney disease and type 2 diabetes. More serious effects include stomach ulcers, vision loss, gout and liver damage.
Over-the-Counter Niacin
You can purchase niacin derivatives -- niacinamide and inositol hexanicotinate -- as over-the-counter supplements. Niacinamide will not treat cholesterol but poses many of the same side effects as regular niacin, although it proves less likely to cause skin flushes. Side effects, including possible allergic reactions, of inositol hexanicotinate remain largely unknown. Some people take large doses of niacinamide in -- unsuccessful -- attempts to pass drug screening tests, eliminate toxins or lose weight. In 2005, more than 3,100 people who took over-the-counter niacin formulas for non-medical reasons called poison control centers to report symptoms such as nausea, rapid heartbeat and vomiting. Majoj Mittal, an emergency room doctor at Children's Hospital in Philadelphia, reported in the April 2007 issue of "Annals of Emergency Medicine" that a person who overdosed on niacin required a liver transplant.
Vitamin B-6
The recommended daily allowance for vitamin B-6 ranges from 1.3 mg to 2 mg. Therapeutic doses to treat pyridoxine deficiency, premenstrual syndrome, pregnancy-related nausea, kidney stones and sideroblastic anemia as well as to help prevent an eye disease called macular degeneration run as high as 600 mg per day. High doses of vitamin B-6 may cause sleepiness, loss of appetite, vomiting and tingling, among other side effects. If you take high doses of B-6 for an extended period, you may develop brain and nerve problems. Pyridoxine will not likely cause an actual allergic reaction -- an unhealthy immune system response.
Considerations
If you take vitamin B-complex supplements, they may contain high amounts of niacin and vitamin B-6, so check the labels. Although allergic reactions to niacin and pyridoxine remain unreported, they could occur. Alert your doctor if you experience any distressing symptoms after taking either. If you believe niacin or B-6 might treat a specific medical condition, discuss possible benefits and risks with your medical provider.
References
- University of Maryland Medical Center; Vitamin B-3 (Niacin); June 18, 2009
- Medline Plus: Niacin and Niacinamide (Vitamin B-3)
- Centers for Disease Control and Prevention; Use of Niacin in Attempts to Defeat Urine Drug Testing -- Five States, January to September 2006; C. Mendoza, M.D.; April 20, 2007
- "Annals of Emergency Medicine"; Toxicity From the Use of Niacin to Beat Urine Drug Screening; Majoj Mittal et al.; April 6, 2007
- MayoClinic.com; Allergies; Jan. 28, 2011
- Medline Plus; Pyridoxine (Vitamin B-6); Dec. 13, 2010
Member Comments