B Complex Vitamin Allergy Causes and Remedies


Believe it or not, some people have allergic reactions to vitamin supplements, including B complex vitamins. Because B vitamins are essential nutrients your body requires regularly to function properly, it's important to know the symptoms of vitamin allergies and how to get relief.

About the Allergy

This vitamin allergy arises when you exhibit symptoms of an allergic reaction after taking B complex vitamin supplements. B complex refers to eight essential B vitamins, which are often found in B complex vitamin supplements. These include vitamin B1 (thiamin), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6, vitamin B7 (biotin), vitamin B12, and folate.

Why Vitamin B Supplements Cause Allergic Reactions

There are several reasons you may experience an allergic reaction after taking B complex vitamin supplements or injections. You might experience side effects of vitamin B toxicity from taking doses that are too high. Flushing, which can happen after ingesting high doses of niacin, is a side effect that can occur even in people without vitamin B allergies. Some B complex vitamin supplements contain over 6,000 percent of your recommended daily value for B. Or, you might be allergic to certain ingredients found in the B complex supplements or injection you're taking. Some people exhibit symptoms of the allergies for unknown reasons.


If you experience symptoms of an allergic reaction within 2 to 10 minutes of taking B complex supplements or vitamin B injections, you may have an allergy to them. Symptoms to watch out for include:

  • Rash
  • Hives
  • Itching
  • Difficulty breathing
  • Wheezing
  • Facial swelling or flushing
  • Chest tightness

You may also experience side effects from too much niacin or vitamin B12 in the supplements or injections, as well.

How to Get Relief

Use the following strategies to get relief when experiencing allergic reactions to B complex vitamin supplements or injections:

Avoid High Doses

Unless told to by your doctor, avoid exceeding tolerable upper intake levels for B vitamins, which include:


Tolerable Upper Intake Level

Vitamin B1 (thiamin)

Not established

Vitamin B2 (riboflavin)

Not established

Vitamin B3 (niacin)

35 milligrams daily

Vitamin B5 (pantothenic acid)

Not established

Vitamin B6

100 milligrams daily

Vitamin B7 (biotin)

Not established

Vitamin B12

Not established


1,000 micrograms daily

If you experience an allergic reaction after taking B complex vitamin supplements or injections, stop taking them immediately and talk with your doctor.

Get B Vitamins From Food

Because your body needs essential B vitamins regularly, try to get your daily dose of vitamin B from foods instead of supplements to avoid allergic reactions.

Desensitize With Small Doses and Build Up

You can also chat with your doctor about desensitization strategies, especially when you're taking vitamin B injections. For example, the American Academy of Allergy, Asthma and Immunology says studies show receiving smaller, more frequent doses of vitamin B12 injections instead of larger doses for a period may help reduce symptoms in patients experiencing allergic reactions.

Living With the Allergy

Being allergic to B complex vitamin supplements doesn't mean you should avoid B vitamins, as these vitamins are essential nutrients your body needs. Talk with your doctor about other ways to meet daily vitamin B requirements, such as getting vitamins from foods, taking smaller doses of B vitamin supplements, or trying desensitization strategies when receiving vitamin B injections.

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B Complex Vitamin Allergy Causes and Remedies