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Skin Rashes From Vitamin B12

author image Jon Williams
Jon Williams is a clinical psychologist and freelance writer. He has performed, presented and published research on a variety of psychological and physical health issues.
Skin Rashes From Vitamin B12
People become more vulnerable to vitamin B12 deficiency as they age. Photo Credit Dougal Waters/Digital Vision/Getty Images

Vitamin B12 helps in the creation of red blood cells, which deliver oxygen to cells throughout your body. Also, vitamin B12 helps to maintain the nervous system and participates in metabolism, which is the breakdown of carbohydrates, protein and fat to provide energy to operate, maintain and repair your body. When you have a vitamin B12 deficiency, you feel tired and weak. Some people develop skin rashes from vitamin B12 deficiency. Ironically, skin rashes can also occur as a response to supplement treatment for B12 deficiency.

Why Supplements are Necessary

Most people obtain sufficient B12 from the food they eat, including shellfish, fish, beef, lamb, cheese and eggs. Deficiencies usually occur when the person is missing a protein called intrinsic factor that helps them absorb vitamin B12. Several conditions can lead to problems absorbing vitamin B12, such as pernicious anemia, gastric bypass surgery, celiac disease, bacteria growth in the small intestine and Crohn's disease. People are more prone to develop vitamin B12 deficiencies as they age. Heavy alcohol consumption and certain drugs can also disrupt B12 absorption. Vegetarians can usually get sufficient B12 from dairy they eat. Vegans must take supplements to meet their B12 needs.

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Symptoms of B12 Deficiency

Symptoms that may indicate you need supplemental vitamin B12 can include fatigue, pale skin, sore tongue, bleeding gums, weight loss, diarrhea, constipation, numbness or tingling in fingers and toes, balance problems, depression, loss of mental abilities, and for some people, skin rashes. If B12 deficiency is suspected, your physician can do a blood test to evaluate levels of B12 and likely other B vitamins including folic acid.

Treatment of B12 Deficiency

Often, doctors treat anemia through injections of hydroxo-B12, methyl B-12 or cyano B-12. Shots are typically given daily for a week, then once a week for a month, then monthly. You can learn how to give yourself shots or a family member can learn how to give the shots. If the anemia is not too severe, doctors may prescribe oral, sublingual --- which is under-the-tongue --- or nasal forms of B12 supplements. In any case, you usually cannot take too much B12. Your body absorbs what it can use, stores it in your liver and excretes the excess.

Side Effects

Side effects of B12 supplements are rare, according to Southern Care Healthcare Group, and generally occur with the injections and not with oral supplements. Side effects can include pain at the injection site, dizziness, diarrhea, nausea, headache, vomiting, acne and skin rash. Some people have allergic or hypersensitive responses to the injection. Allergic responses can include shortness of breath, swelling of the face, lips tongue or other body parts and rash, hives or itching. Some people have immediate responses to an injection, but for others it can take several days to several weeks of injections for the allergic responses to appear.


If you develop a rash, hives or other skin condition in response to B12 shots, speak with your doctor immediately. You may have hypersensitivity, and you will likely continue to have adverse responses as long as you continue injections. Your doctor may choose to have you try sublingual, nasal or oral forms of B12 supplements. If you discontinue B12 injections it may take as long as 4 months for your rash to clear up.


If your skin turns red vitamin B12 supplementation, you may be prone to develop photosensitivity, which is unusual sensitivity to sunlight or artificial UV rays. Avoid going out into the sun, wear sunscreen and wear protective clothing if you do go out. Speak with your doctor regarding your side effects.

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