What are Vitamin B6 Side Effects?

Troy Holmes

Vitamin B6 is usually considered safe for humans, and there aren’t typically any side effects associated with small amounts. Problems can arise when people ingest more than their bodies need, or if they take supplements that their bodies have a hard time processing. The most serious side effects include a range of neurological issues, including numbness, muscle spasms, and brain chemistry imbalances that can lead to more serious complications like seizures. The vitamin has also been shown to cause shortness of breath and wheezing in some patients, and can also lead to rashes and skin eruptions like acne; nausea, vomiting, and intestinal cramps can happen, too. Somewhat paradoxically, women often use this vitamin to actually relieve things like nausea and vomiting during pregnancy, but this class of patients usually has to be really careful not to consume too much. Excessive B6 intake during pregnancy has been linked to some birth defects as well as an increased rate of seizures in newborns.

Mental confusion can be caused by a vitamin B6 deficiency.
Mental confusion can be caused by a vitamin B6 deficiency.

Vitamin Basics

Most B vitamins, including B6, are readily found in many foods, particularly fruits, vegetables, and meats. B6 is also available as a dietary supplement in many places, either on its own or along with other minerals in a multivitamin compound. Side effects are usually only observed in people who take high concentrations of the vitamin in a supplement. When it occurs in nature, it’s usually in small enough amounts that it would be hard for a person to get enough to cause a reaction.

Nausea, vomiting, and intestinal cramps are possible side effects of vitamin B6.
Nausea, vomiting, and intestinal cramps are possible side effects of vitamin B6.


The normal dosage for B6 supplements is approximately 100 milligrams per day. Vitamin B6 side effects typically begin to become more apparent when the daily dosage is exceeded. Most people can get all that they need from their regular diet, and supplementation is something that should usually be discussed with a qualified healthcare provider. Medical experts will have a better sense of the risks particular patients may face, and can give more personalized advice.

Vitamin B6 may cause fatigue in some individuals.
Vitamin B6 may cause fatigue in some individuals.

When taken as a normal daily vitamin, B-complex vitamins can increase metabolism, energy, immune system and overall mood. All B vitamins are water-soluble but caution should be taken if B6 is used as an individual supplement in conjunction with a combined daily vitamin. This may cause an unintentional over consumption and an individual may quickly demonstrate side effects.

Most B-complex supplements contain vitamin B6.
Most B-complex supplements contain vitamin B6.

Neurological Damage

Pyridoxine, the primary chemical ingredient of B6, is a primary contributor to the overall management of the nervous system. As a consequence, some of the most dangerous and significant side effects are neurological. People who have a prolonged pattern of excessive vitamin use can experience numbness and loss of overall coordination, as well as diminished brain function in rare cases. There is sometimes a connection between overdose and seizures, though this is usually considered very extreme and a person normally has to consume a lot all at once for symptoms to get this serious.

Bananas contain vitamin B6.
Bananas contain vitamin B6.

Respiratory and Skin Problems

Skin rashes and breakouts can happen, too, normally as a reaction to excess B6 that the body is trying to process out. Some people also experience breathing difficulty, diminished lung capacity, and asthma-like wheezing. Again, though, in nearly all cases the only people who experience these sorts of symptoms are those who have taken the vitamin in supplement form. Many supplements contain hundreds of times the amount when compared to natural sources, and it’s very rare for people to have a reaction to a single vitamin in a food.

Those who take vitamin B6 supplements may experience stomach cramps.
Those who take vitamin B6 supplements may experience stomach cramps.

Digestive Distress

Supplement takers sometimes also feel nauseous, may experience stomach cramps, and could suffer from brief bouts of diarrhea. Most of the time these are short-lived, and will usually dissipate once the body acclimates. Any digestive trouble that lasts more than a week or so should probably be evaluated by a medical professional.


Vitamin B6 side effects become readily apparent in patients that acquire B6 toxicity. This can occur when individuals take dosages higher then 200 mg per day. Extreme cases of toxicity have caused swelling in the lips and throat, vomiting, and numbness in all extremities. In the event of toxicity, an individual should seek medical attention immediately.

Special Concerns in Pregnancy

Women who are pregnant are sometimes advised to take this vitamin because of its potential to help calm morning sickness and nausea in the early stages of pregnancy. Many prenatal vitamins actually include it in their formulas for this reason. There is some risk when it comes to very high doses, though, and women are usually advised to use the vitamin in moderation. Overdoses have been shown to cause birth defects and newborn seizures.

Problems Related to Vitamin Deficiency

A deficiency in B6 also can cause health problems. In extreme cases, this deficiency leads to problems including mental confusion, skin scars, and decreased immunity. Typically these low levels are found in individuals with kidney problems, people with alcohol addiction, and people on extreme diets.

Vitamin B6 can be found in tuna.
Vitamin B6 can be found in tuna.

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Discussion Comments


Although the vitamin b 6 side effects can be very serious, it is important to not take things too far the other way and forget about all the benefits of vitamin b6.

The most common vitamin b6 benefits include maintaining healthy muscles and nerves. It is also extremely important for building DNA and RNA, as well as producing red blood cells and other cells that help with the immune system.

So although the side effects of vitamin b6 toxicity are very serious indeed, don't forget that you still need to get the appropriate dosage -- otherwise you could experience a whole different set of dangerous side effects.


This article was very helpful in my research on the side effects of vitamin B6. I had to learn about all of the possible b vitamin complex side effects for a presentation, and this article gave me the clearest explanation, and the most side effects.

Thanks for writing it.


I'm so glad that you wrote this article! I was looking at a vitamin B complex vitamin because I had heard all these great things about vitamin B benefits, but the only dosage I could find was for 2000 mg a day!

I can only imagine what kind crazy side effects that vitamin b complex has. Those side effects that you list are really scary, so I can't even consider what taking 2000 mg a day would do.

Thanks for cluing my in wisegeek -- I will definitely be paying closer attention to my vitamin ingredients from now on.

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