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Vitamin B12 Overdosing - Any Serious Consequences?

Vitamin B12 Overdosing - Any Serious Consequences?
Dr. Constance Odom, MD Picture of Dr. Constance Odom, MD

Medically reviewed by

Written by our editorial team.

Last Edited 7 min read

If your doctor prescribed Vitamin B12 for deficiencies or you are considering the use of supplements to help increase low levels of B12, the use of supplements is an obvious solution to your problem. With this in mind, there are many questions you might have as it relates to dosage, potential overdose, and whether supplements can interfere with other medications you are taking. If you are worried about potential overdose when using supplements to treat a deficiency, these are some facts which might help you decide whether or not using Vitamin B12 supplements is the right approach for you. If you want to read the further benefits of Vitamin B12 click here.

Can you overdose on Vitamin B12?

Too much vitamin B12, is it possible? Yes it is possible that you take more than the prescribed dosage; however, this vitamin is not toxic in higher levels than have been prescribed, so toxicity concerns aren't something you have to worry about when using the supplement to treat a deficiency. Vitamin B12 is a water-soluble vitamin helping maintain red-blood cell levels and nerve cells. Being water soluble means it is not toxic.

With this being said, in the event you do take more than your prescribed dosage, it is always possible that you skip a dose the next day, or that you minimize dosage over the coming days. For example, if you take 5000 mcg each day, and you mistakenly take two one day, you can opt to skip taking your supplement the next day. Conversely, you can cut the pill in half for a couple days, until you reach the dosage level which has been prescribed to you.

Even in the event of an "over"dose, you do not have to worry about the vitamin B12 being toxic or otherwise harmful to your health. At worst, you may feel overly energized. You can always speak to your doctor about not taking the supplement one day, or other alternatives, in the event you do take too much, or more than was initially prescribed to you.

Are there dosage limits based on age?

Although dosage levels are not technically determined by your age group, people who are over the age of 50 do experience decreased absorption rates. This is not only with Vitamin B12, but with other essential vitamins and minerals the body needs on a daily basis as well. So, although you won't be prescribed 1000 mcg because you are 55 years old, versus 500 mcg if you are 35 years old, your age does technically provide some guidance as to how much you should take daily.

In addition to your age however, other factors might determine the appropriate dosage you will be prescribed when taking Vitamin B12 supplements. If you are at a genetic disposition, and suffer from other deficiencies (in addition to B12 deficiency), your dosage might be higher than another individual who doesn't suffer such genetic problems. Your diet is a big contributor as well. B12 is found in red meats, fish, milk, yogurt, and other foods. Individuals who are vegan or vegetarian might suffer from deficiencies and require a higher dosage. Others who make poor dietary choices, or do not consume foods which are rich in B12 might also require use of a supplement. And, those who eat a diet which is rich in Vitamin B12, and other essential vitamins and minerals, might not require supplements at all.

Your diet, other health factors, your daily activities, work you do, and yes, your age, are all going to be contributing factors when it comes to determining dosage levels for Vitamin B12. And ,the older you get the less your body naturally absorbs the vitamin, meaning a higher dosage is probably going to be prescribed as you age. However, age alone is not the indicating factor which will determine dosage levels of B12, or other supplements and prescription medications you take on a routine basis.

Read more about Vitamin B12:


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What potential Side Effects will an Overdose cause?

Again, toxicity is not of concern if you overdose on Vitamin B12 supplements. As it is water soluble, your body will readily absorb and digest it naturally, so it will simply "pass through" your system over the coming days and weeks if the levels at which you overdosed were extremely high.

However, in the event of an overdose, there are certain symptoms you might experience, which you should be aware of, simply so you do not worry that other health risks are present. Reddening of the skin is one of the most common side effects you might experience if you consume too much vitamin B12. Reddening of the urine is also possible, so don't automatically assume the worst if you have consumed high levels of the vitamin.

Vasodilation is also possible. Since it might cause the blood vessels in your body to expand, this dilation of your blood vessels can possibly lead to decreases in blood pressure levels for a short period of time following the overdose. Some people complain of itchiness and dry skin when they consume too much vitamin B12 as well.

An overdose does not technically mean you are going to experience all of these (or mean you will experience any of these) side effects. It is however important to note that they might occur, and if they do, that you should not worry you are suffering from other health-related issues which should be alarming or dangerous to your mental health and overall well-being.

Vitamin B12 is essential, as is the case with other vitamins and minerals. The fact that most of us do not get sufficient levels from diet alone, means a supplement is going to help naturally increase levels of the vitamin in our bodies. And, in the event we take too much of the vitamin, certain side effects can occur, which others have experienced and reported in the past following an overdose.

With this in mind, it is important to note that an overdose is not at all harmful or highly dangerous to your health and well-being. At worst, you might have itchy skin or blotched red marks on your skin for a few hours (or possibly a bit longer). But, the water soluble vitamin is safe, and will not cause complex health risks if consumed in higher levels than prescribed.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your physician about the risks and benefits of any treatment. Nu Image Medical may not offer the medications or services mentioned in this article.