Vitamin B12 belongs to the group of cobalt containing B complex vitamins that is necessary for normal cell activity and very important in maintaining a healthy central nervous system and red blood cell formation. One of its important characteristic is, it is a water soluble vitamin thus toxicity or overdose will not likely occur. Vitamin B12 is found abundant in most food which comes from animal products such as liver, fish, meat, shell fish, and dairy products.

What’s great with B12 is even if it was given in a large dose it is non-toxic. However, some people have experienced adverse reaction, even though such events rarely occur. Most of the times, vitamin B12 is given orally which means there is only a little chance of toxicity to occur because it undergone various process thus its concentration is decreased when absorbed. But some people choose to take B12 injections rather than oral ingestion, especially those who have problem on its absorption. This type of route is associated with the following side effects:

- mild diarrhea
- anxiety and panic attacks
- palpitations
- insomnia
- breathing problems
- chest pain
- skin rash, hiver or itchy swollen skin

But some health professionals believe that patients develop such reaction not because of the Vitamin B12 itself but due to the preservatives that are incorporated in the formula. At this time most of the formula contains preservatives. So to decrease your anxiety while having B12 supplementation it is safer to take it orally. And for those who have allergy to cobalt it would be better if you will not take supplementation and be advised to consume foods with vitamin b12. Vitamin B12 should be given in caution for patient’s having coronary heart problems because it causes narrowing of the vessels that might increase the risk of heart attacks. In addition it must be avoided by patients who have Leber’s disease because it actually speeds up the atrophy of the optic nerve resulting to rapid loss of vision. On the positive side, B12 can be taken by pregnant and lactating women as long as they are not exceeding the recommended daily allowance.

As you can see, Vitamin B12 is a safe vitamin with very few side effects even in large dose. More problems arise from vitamin b12 deficiency rather than its ingestion.