What Are Side Effects of Vitamin B12 Tablets?
Vitamin B12, also known as cobalamin, is one of the largest and most complex vitamins. Several biological processes require vitamin B12, and deficiencies of this vitamin can cause several health conditions, including anemia. While vitamin B12 is generally safe, some side effects may occur. As with any health supplement, you should consult your doctor before taking vitamin B12.
Vitamin B12 is a water-soluble vitamin, meaning if you take too much, the excess amounts are easily flushed from the body through urine. As a result, taking large doses of vitamin B12 rarely results in toxicity. Current research suggests that you can safely take up to 1 milligram of vitamin B12 per day and experience no major side effects, reports the Linus Pauling Institute at Oregon State University.
Does Vitamin B12 Make You Lose Weight?
In rare cases, certain individuals may experience a severe allergic reaction to vitamin B12, which contains a metal ion, cobalt, and anyone allergic to cobalt will also be allergic to vitamin B12. Symptoms of an allergic reaction include swelling of the hands, face, neck, mouth or tongue. Dizziness, difficulty swallowing or breathing and unconsciousness can occur during serious allergic reactions. If you experience these symptoms after taking vitamin B12, contact your doctor immediately.
- In rare cases, certain individuals may experience a severe allergic reaction to vitamin B12, which contains a metal ion, cobalt, and anyone allergic to cobalt will also be allergic to vitamin B12.
- If you experience these symptoms after taking vitamin B12, contact your doctor immediately.
Additional Side Effects
Some people might experience a variety of mild side effects after taking vitamin B12, such as temporary itching, rash or rosacea fulminans, an intense reddening of the face. Diarrhea also has been reported, Certain individuals may develop an increased risk of blood clots, particularly if vitamin B12 supplements are taken to treat vitamin B12 deficiency. Treatment of a B12 deficiency can unmask a blood disorder known as polycythemia vera, which is characterized by increased red blood cells and blood volume.
Can You Be Allergic to Vitamins?
People with a rare, hereditary optic nerve disease known as Leber's disease should not take vitamin B12 supplements. Doing so may result in a rapid, severe atrophy of the optic nerve. People who have recently received a coronary stent though angioplasty should avoid vitamin B12. After the placement of coronary stents, patients often receive high doses of vitamin B6 or B12, and taking additional vitamin B12 can reduce the effectiveness of the stents and cause a re-narrowing of the arteries.
- People with a rare, hereditary optic nerve disease known as Leber's disease should not take vitamin B12 supplements.
- People who have recently received a coronary stent though angioplasty should avoid vitamin B12.
Does Vitamin B12 Make You Lose Weight?
Can You Be Allergic to Vitamins?
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- MedlinePlus: Vitamin B12
- Linus Pauling Institute at Oregon State University: Vitamin B12
- Holick MF, Gordon CM. Patient Guide to Vitamin D Deficiency. The Journal of Clinical Endocrinology & Metabolism. 2011;96(7):1-2. doi:10.1210/jcem.96.7.zeg33a
- Sunyecz JA. The use of calcium and vitamin D in the management of osteoporosis. Ther Clin Risk Manag. 2008;4(4):827-836. doi:10.2147/tcrm.s3552
- Giovannucci E, Liu Y, Hollis BW, Rimm EB. 25-hydroxyvitamin D and risk of myocardial infarction in men: a prospective study. Arch Intern Med. 2008;168(11):1174-1180. doi:10.1001/archinte.168.11.1174
- Gorham ED, Garland CF, Garland FC, et al. Optimal vitamin D status for colorectal cancer prevention: a quantitative meta analysis. Am J Prev Med. 2007;32(3):210-216. doi:10.1016/j.amepre.2006.11.004
- Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. The American Journal of Clinical Nutrition. 2007;85(6):1586-1591. doi:10.1093/ajcn/85.6.1586
- Prentice RL, Pettinger MB, Jackson RD, et al. Health risks and benefits from calcium and vitamin D supplementation: Women’s Health Initiative clinical trial and cohort study. Osteoporos Int. 2013;24(2):567-580. doi:10.1007/s00198-012-2224-2
- Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr. 2010;91(5):1255-1260. doi:10.3945/ajcn.2009.29094
- Salehpour A, Hosseinpanah F, Shidfar F, et al. A 12-week double-blind randomized clinical trial of vitamin D₃ supplementation on body fat mass in healthy overweight and obese women. Nutr J. 2012;11:78. doi:10.1186/1475-2891-11-78
- Carrillo AE, Flynn MG, Pinkston C, et al. Impact of vitamin D supplementation during a resistance training intervention on body composition, muscle function, and glucose tolerance in overweight and obese adults. Clin Nutr. 2013;32(3):375-381. doi:10.1016/j.clnu.2012.08.014
- Marcinowska-Suchowierska E, Kupisz-Urbańska M, Łukaszkiewicz J, Płudowski P, Jones G. Vitamin D Toxicity-A Clinical Perspective. Front Endocrinol. 2018;9:550. doi:10.3389/fendo.2018.00550
- Ross AC, Manson JE, Abrams SA, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab. 2011;96(1):53-58. doi:10.1210/jc.2010-2704
- Bouillon R, Van Schoor NM, Gielen E, et al. Optimal vitamin D status: a critical analysis on the basis of evidence-based medicine. J Clin Endocrinol Metab. 2013;98(8):E1283-E1304. doi:10.1210/jc.2013-1195
- American Academy of Dermatology. Position Statement of Vitamin D. 2010.
- Taksler GB, Cutler DM, Giovannucci E, Keating NL. Vitamin D deficiency in minority populations. Public Health Nutr. 2015;18(3):379-391. doi:10.1017/S1368980014000457
- Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96(7):1911-1930. doi:10.1210/jc.2011-0385
- Cannell JJ, Vieth R, Umhau JC, et al. Epidemic Influenza and Vitamin D. Epidemiol Infect. 2006; 134:1129-40.
- Carrillo AE1, Flynn MG, Pinkston C, Markofski MM, Jiang Y, Donkin SS, Teegarden D. Impact of Vitamin D Supplementation During a Resistance Training Intervention on Body Composition, Muscle Function, and Glucose Tolerance in Overweight and Obese Adults. Clin Nutr. 2013 Jun;32(3):375-81. doi: 10.1016/j.clnu.2012.08.014. Epub 2012 Aug 31.
- Ginde AA, Mansbach JM, Camargo CA, Jr. Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey. Arch Intern Med. 2009; 169:384-90.
- Giovannucci E, Liu Y, Hollis BW, Rimm EB. 25-hydroxyvitamin D and Risk of Myocardial Infarction in Men: a Prospective Study. Arch Intern Med. 2008; 168:1174-80.
- Gorham ED, Garland CF, Garland FC, Grant WB, Mohr SB, Lipkin M, Newmark HL, Giovannucci E, Wei M, Holick MF. Optimal Vitamin D Status for Colorectal Cancer Prevention: a Quantitative Meta-analysis. Am J Prev Med. 2007 Mar;32(3):210-6.
- Heaney, Robert P. “The Vitamin D Requirement in Health and Disease.” The Journal of Steroid Biochemistry & Molecular Biology 97 (2005):13-9.
- Holick MF. Vitamin D. In: Shils M, Olson J, Shike M, Ross AC, ed. Modern Nutrition in Health and Disease, 9th ed. Baltimore: Williams and Wilkins, 1999.
- National Institutes of Health Office of Dietary Supplements. Vitamin D: Dietary Supplement Fact Sheet. University of Ottawa Evidence-based Practice Center. Effectiveness and Safety of Vitamin D in Relation to Bone Health. Agency for Healthcare Research and Quality. Aug 2007: 07-E013.
- Salehpour A1, Hosseinpanah F, Shidfar F, Vafa M, Razaghi M, Dehghani S, Hoshiarrad A, Gohari M. A 12-week Double-blind Randomized Clinical Trial of Vitamin D₃ Supplementation on Body Fat Mass in Healthy Overweight and Obese Women. Nutr J. 2012 Sep 22;11:78. doi: 10.1186/1475-2891-11-78.
- Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H. Randomized Trial of Vitamin D Supplementation to Prevent Seasonal Influenza A in Schoolchildren. Am J Clin Nutr. 2010 91:1255-60. Epub 2010 Mar 10.
- Wilkins, Consuelo H. and Yvette I. Sheline, et al. “Vitamin D Deficiency Is Associated with Low Mood and Worse Cognitive Performance in Older Adults.” American Journal of Geriatric Psychiatry 14 (2006): 1032-40.
Matthew Busse has pursued professional health and science writing since 2007, writing for national publications including "Science Magazine," "New Scientist" and "The Scientist." Busse holds a doctorate in molecular biology from the University of California-San Diego.