Here's Why Vitamin B Can Cause Rashes, Hives, and Flushing

Here's Why Vitamin B Can Cause Rashes, Hives, and Flushing

Here's Why Vitamin B Can Cause Rashes, Hives, and Flushing
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By
Andra Picincu, CN, CPT
Updated on October 16, 2025
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B vitamins are essential nutrients that help your body function at its best.

But these nutrients may irritate your skin — leading to rashes, hives, or other symptoms — especially if you take too much.

Here’s what the research says about vitamin B and skin–related side effects.

What Are B Vitamins?

B vitamins help your body process energy and form red blood cells, according to the MedlinePlus. There are many varieties of the vitamin, including:

  • B1 (thiamine)
  • B2 (riboflavin)
  • B3 (niacin)
  • B5 (pantothenic acid)
  • B6
  • B7 (biotin)
  • B12
  • Folic acid

Food is the best source of this nutrient. According to the NLM, good sources of vitamin B include:

  • Fish like salmon
  • Poultry like chicken and turkey
  • Meat like beef or lean pork chops
  • Leafy greens like spinach
  • Legumes like beans, peas, and lentils

Still, many people choose to get more vitamin B by taking a supplement.

The Problem With Vitamin B Supplements

The U.S. Food and Drug Administration (FDA) doesn’t require supplements to be proven safe or effective before they’re sold. But even the highest-quality product might cause skin flushing, hives, or rashes.

That’s because it’s potentially unhealthy to take dietary supplements and injections that contain large doses of B vitamins, especially over the long term. Overdosing on B vitamins may increase the risk of side effects and allergic reactions.

It’s worth knowing that most B vitamin supplements far surpass the daily recommended dose, because your body absorbs much less of the vitamin when it’s taken by mouth, according to the National Institutes of Health (NIH).

Side Effects of Taking Too Much Vitamin B

Symptoms may vary depending on which type of B vitamin you’re taking.

For example, too much vitamin B6 may cause severe skin lesions, along with other symptoms like numbness, digestive issues, and poor muscle control, according to Mayo Clinic.

Vitamin B12 can cause dermatitis, acne, and other skin-related conditions when taken in excess, according to a review in the American Journal of Clinical Dermatology.

These reactions are typically the result of taking high doses of a supplement, according to Mayo Clinic. Getting vitamin B from food alone isn’t likely to bring on symptoms.

You May Have a Vitamin B Allergy

Vitamin B allergies are rare, but there are a few studies on the subject. One study in the The Journal of Allergy and Clinical Immunology found that some injected forms of B vitamins at higher doses, like B12, can be linked with an allergic reaction.

Talk With Your Doctor

If you have a skin reaction to any type of vitamin B supplement, stop using it and ask your doctor how to proceed.

In general, it’s a good idea to speak with a healthcare professional before you take any new supplement. They can figure out the best dose (and source) of the nutrient for you.

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Justin Laube

Justin Laube, MD

Medical Reviewer

Justin Laube, MD, is a board-certified integrative and internal medicine physician, a teacher, and a consultant with extensive expertise in integrative health, medical education, and trauma healing.

He graduated with a bachelor's in biology from the University of Wisconsin and a medical degree from the University of Minnesota Medical School. During medical school, he completed a graduate certificate in integrative therapies and healing practices through the Earl E. Bakken Center for Spirituality & Healing. He completed his three-year residency training in internal medicine at the University of California in Los Angeles on the primary care track and a two-year fellowship in integrative East-West primary care at the UCLA Health Center for East-West Medicine.

He is currently taking a multiyear personal and professional sabbatical to explore the relationship between childhood trauma, disease, and the processes of healing. He is developing a clinical practice for patients with complex trauma, as well as for others going through significant life transitions. He is working on a book distilling the insights from his sabbatical, teaching, and leading retreats on trauma, integrative health, mindfulness, and well-being for health professionals, students, and the community.

Previously, Dr. Laube was an assistant clinical professor at the UCLA Health Center for East-West Medicine and the David Geffen School of Medicine at UCLA, where he provided primary care and integrative East-West medical consultations. As part of the faculty, he completed a medical education fellowship and received a certificate in innovation in curriculum design and evaluation. He was the fellowship director at the Center for East-West Medicine and led courses for physician fellows, residents, and medical students.

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Andra Picincu, CN, CPT

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