<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=854433617968739&amp;ev=PageView&amp;noscript=1">
  • "My weight was getting so out of control. I started their weigh loss diet program and lost 32 lbs! I have been able to reduce my blood pressure medicine, fit back in my clothes, have tons more energy... Now I am back to eating and my desire for foods has changes drastically. Saved my life!!!
    Pamela, Scottsdale Az
  • "Dr. Cline and Dr. Terranella have been amazing! For the first time we found doctors that actually listen. They care about how your feeling and try everything they can to get you back to a normal state. I am in love with these guys! If you want amazing care, see these guys."
    Jennifer F. ,Phoenix Az

Why Your B12 Shots Are Not Working

Vitamin B12 and vitamin b12 shots have a long list of potential health improvement claims from low energy to neuropathy. The question is are these claims valid and if so what are some reasons b12 shots would not actually live up to their potential?


What are B12 Shots?

First let's cover the basics. Vitamin B12 is a water soluble vitamin also known as cobalamin. The cobalmin molecule can be combine with a cyanide molecule as in cynaocobalmin, a hydroxyl molecule as in hydroxycobalmin, methyl group as in methylcobalmin, or an adenosine molecule as in adenosylcobalmin.  All of these are considered b12 and all of these have specific affinities and activities in the body, except for cyanocobalmin.  All are available in oral form and sublingual form but not (mainly adenosylcobalmin) all forms are available as a b12 shot.

As a whole b12 serves as co-factor for many reactions in the body including proper functioning of the nervous system, metabolism, neurotransmitter production, DNA repair, cell membrane production, and more. For instance, because of its role in DNA repair, it is essential for cell division and plays a significant role in the formation and repair of all cells. Because of its connection to so many aspects of normal human health, b12 deficiency can manifest itself with many symptoms. These include:

  • Numbness, tingling, neuropathy, or buzzing sensation anywhere in the body.
  • Fatigue, depression, low motivation.
  • Anxiety, poor sleep quality, or insomnia.
  • Poor exercise recovery and injury prone. 
  • Problems with memory
  • Shortness of breath and weakness
  • Problems with coordination and balance

When a b12 vitamin deficiency is suspected, supplements can be given either in the form of oral pill, sublingual lozenges, or vitamin B12 injections also known as “B12 shots”. So when you are getting a b12 shot, when should you expect it to work?

Still tired after b12 shots

Is Your B12 Shot Working?

The typical course for B12 shots is to give a few injections in the first month (one per week) at 1000mcg per shot and then start to spread them out.  This is a rough guide and can be adjusted based on symptom severity and the severity of deficiency.  The thing we have to keep in mind when treating b12 deficiency is that often times the symptoms have taken years to manifest and we may not see a noticeable change after 1-2 shots.  That said, however, in most people I usually see a noticeable (although not always lasting) improvement after 2-3 shots. Sometimes the change will only last a few days and revert back to the previous health state.  The most common noticeable change is in energy or clarity of thought.

So what do you do if you are not getting the expected outcome from your b12 shots?


Reasons Your B12 Shot Is Not Work

1. The Form of vitamin B12

As noted above there are several different forms of B12. Unfortunately the most commonly used is not the best form. Cyanocobalamin is the commonly used form of vitamin B12 injections (Carmel, 2008).  This form of b12 is not as effective because it is not in a usable form. The better version is methylb12 or methylcobalmin. The methyl group is what gives b12 it's medicinal quality. The cyano version has to be turned into methyl version in order to have any effect. The body can do this but many times the reason the deficiency exists is  because there is some venerability with formation of methyldonors (like methylcobalmin).  We should note that methylcobalmin does start to breakdown when exposed to light so it should be kept out of direct light. 


2. Expectations are off

What were you expecting to happen? If you had b12 deficiency for a long time it may take months before you see a regression of your symptoms. In our naturopathic clinic in Phoenix we initially see improvement in energy and mental states.  Neurological issues like neuropathy may take longer, up to 3-6 months (Carmel, 2008).  Improvements in red blood cell count could take months of regular b12 shots to see improvement. 

3. Wrong diagnosis

Neurological, psychological, metabolic, and hematological symptoms seen in B12 deficiency can be caused by other disease conditions. Non response to B12 injections should therefore necessitate re-evaluation and consideration of other diagnoses.  For instance, hormonal imbalance (like hypothyroid) can have overlapping symptoms pictures as can various autoimmune diseases. 

4. Deficiency of other important vitamins or micronutrients

Because it has overlapping physiological roles in the body, a folate deficiency can have a very similar clinical picture to B12 deficiency. Such as the symptoms listed above and on laboratory evaluation. With b12 deficiency there can be an enlargement of red blood cells called macrocytiosis. This picture can also be caused by folate deficiency.  Iron deficency and other nutrient deficiencies can also cause similar symptoms. 


5. Inappropriate dosage

As stated above B12 shots need to be adjusted based on the degree of deficiency and clinical assessment. Some people have genetic alterations in their ability to process b12 that requires them to get b12 more often and in higher quantities than the average person. 

6. Development of auto-antibodies

Some cobalamin preparations in rare cases can stimulate an allergenic response where there is development of antibodies to the cobalmin injected. This will subsequently form complexes with the cobalmin and thereby reduce its efficacy. Again this is rare and likely has more to do with preservative and other things in the injection other than cobalmin since our bodies need this molecule to survive. 


There is no doubt that vitamin b12 shots can be extremely helpful in improving the health of many people when they are lacking optimal levels for various reasons.  Getting the correct dose, form, and frequency are important aspects of realizing the benefits of your b12 shots. Additionally making sure your health issues are caused by b12 and not folate is also an important distinction to make. 


So what about you, have you had a good experience with your b12 shots or did they not wok for you?

Let us know in the comments below.

Reference list
Carmel, R. (2008). How I treat cobalamin (vitamin B12) deficiency. Blood, 112(6), pp.2214-2221.

Little DR.(1999).Ambulatory management of common forms of anemia. Am Fam Physician. 59(6):1598-1604.

Recent Posts

Width: 420px   Height: 622px
New Call-to-action
New Call-to-action
New Call-to-action
New Call-to-action
Digestive Reset
Don't B12 Deficient