iCliniq logo

Ask a Doctor Online Now

HomeAnswersHematologyfatigue syndromeDo Vitamin B12 injections help fatigue?

Shall I take injectable vitamin B12 to improve my fatigue symptoms?

The following is an actual conversation between an iCliniq user and a doctor that has been reviewed and published as a Premium Q&A.

Medically reviewed by

iCliniq medical review team

Published At October 27, 2016
Reviewed AtJune 7, 2023

Patient's Query

Hi doctor,

I have been diagnosed with chronic fatigue syndrome. I am taking 0.11 oz of Valtrex a day, which increased from 0.07 oz for four months. Until a month ago, my CFS seemed to be improved. Then last month, I had a major setback with the return of symptoms beyond fatigue, such as heart palpitations, tinnitus, tingling or burning in hands and feet, balance problems, shortness of breath, loss of appetite, and a new set of stomach pains with occasional diarrhea. I am taking B12 and folic acid orally and my last B12 test was high. I think 1600. My blood work has been borderline pretty consistent for years and it is followed by the most recent CBC, which was taken last month and is as follows. HCT around 37, 35.7; HGB around 12, 12.6; MCH around 34, 36.5; MCHC around 32.5, 35.2; MCV around 101, 103.9; platelets 146 to 119, 152; RBC around 3.6, 3.44 and WBC around 4.2, 4.5.

My doctor has told me that these results are not significant and cannot be an explanation for my recent major relapse. I read a recent case report where the B12 blood test does not always mean that the B12 is being absorbed or used by the body. Is there any possibility that this minor turndown could be responsible for symptoms? Is there any downside to start injectable B12 to see if it makes a difference? Are there any additional blood tests that might clarify this? I know that the dosage of Valtrex is high and that antiviral can affect CBC.

Answered by Dr. Prakash. H. M.


Welcome back to icliniq.com.

Based on your query, my opinion is as follows:

  1. Hemoglobin levels are good and should not be causing any of these symptoms. It appears to be more related to medication adverse effects.
  2. Vitamin B12 levels are high and injectable B12 will only increase it. Improvement in the utility of B12 will not occur. As oral absorption is good, no need to go for injectable B12.
  3. Blood work is good and no additional tests are necessary. You need to continue the same treatment.
  4. The adverse effects of medication require management. It is not related to blood. For blood to cause some of these symptoms, all the values need to fall by at least 50%.

Same symptoms don't mean you have the same problem. Consult a doctor now!

Dr. Prakash. H. M.
Dr. Prakash. H. M.


Community Banner Mobile
By subscribing, I agree to iCliniq's Terms & Privacy Policy.

Ask your health query to a doctor online


*guaranteed answer within 4 hours

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.

This website uses cookies to ensure you get the best experience on our website. iCliniq privacy policy