Vitamin deficiencies are supposed to be a thing of the past. But a lack of vitamin B12 may be surprisingly common.

Most people don’t think twice about this nutrient, also known as cobalamin. Vitamins B, C and D are sexier and get more attention. But inadequate levels of vitamin B12 can have devastating consequences:

“I want to warn your readers about my experience with tetracycline. This antibiotic was prescribed by a dermatologist to keep my skin clear and I took it for years.

“Gradually I began having difficulties such as burning, tingling and numbness in my fingers and feet. I lost a lot of hair, which was once my best feature. Even worse, my short-term memory became very poor. I am an attorney and this affected my work.

“I was having trouble walking when I noticed a poster in the pharmacy describing the symptoms of vitamin B12 deficiency. I realized that I had all of them. When I was tested, the doctors were astonished that my B12 levels were so low.

“They started vitamin B12 injections twice a week and then gradually changed me to twice a month. My hair has grown back and my nerve problems are much better, though not perfect. The tetracycline was the culprit.”

It took a long time for this woman’s problem to be diagnosed. Her doctors had not considered the possibility that her many symptoms could be due to a drug-induced lack of cobalamin.

Symptoms of vitamin B12 deficiency include:

anemia, nerve damage (burning, tingling, weakness or numbness in hands and feet), difficulty in sensing vibration, unsteadiness and psychological side effects. Depression, confusion and poor memory may be mistaken for early onset of Alzheimer’s disease.

This vitamin deficiency often appears very gradually. Patients may describe complaints such as mental fuzziness or poor coordination for months before a proper diagnosis is made.

Few people realize that certain medications can interfere with the absorption of this crucial nutrient. Acid in the stomach is essential for this function, so long-term use of strong acid-suppressing medications such as Aciphex (rabeprazole), Nexium (esomeprazole), Prevacid (lansoprazole), Prilosec (omeprazole), or Protonix (pantoprazole) may contribute to a problem for some individuals, especially when taken for a long period of time.

The diabetes medicine Glucophage (metformin) can also lead to problems with vitamin B12. Anyone taking this drug should be monitored very carefully and supplementation may be necessary. Potassium supplements such as Slow-K, Micro-K, Kaon Cl, K-Tab and Klor-Con can also wreak havoc with cobalamin levels.

Older people may be especially susceptible to this deficiency. As we age, the stomach can become less acidic. It may also stop making a key chemical called intrinsic factor, which promotes vitamin B12 absorption.

Seniors are not the only vulnerable population. Vegetarians, especially teenage girls who are not as nutrition savvy, may also suffer. Dutch researchers recently reported adolescents on a strict vegetarian diet performed poorly on a battery of tests designed to evaluate mental ability and coordination.

You may think vitamins are boring, but the consequences of a deficiency are devastating. Sometimes even a well-balanced diet cannot overcome the vitamin-depleting effects of medication.


Join Over 115,000 Subscribers at The People's Pharmacy

Each week we send two free email newsletters with breaking health news, prescription drug information, home remedies and a preview of our award-winning radio show. Join our mailing list and get the information you need to make confident choices about your health.

  1. lulu
    Erie pa

    I was on injections years ago…..a pharmacist told me that 1,000 mg of B12 was the same as a shot but you must take it every day, The newer physicians out of med school give the pills NOT the shots.

  2. eac

    For those asking about natural sources of B12, this is the vitamin found in animal sources: fish, meat, poultry, eggs. Vegetarian sources rely on brewers yeast and algal sources. The most dense natural source (in addition to other vitamins and iron) is liver…as its an organ meat I would recommend liver from a pastured grassfed/finished animal.

  3. Sara Chapman

    I read that taking it via a SUBLINGUAL (under the tongue) pill is just as effective as injections! And much cheaper and more convenient as well. That is because the vitamin is absorbed directly into the bloodstream via the mucus membranes of the mouth without having to go through the digestive tract, which frequently cannot absorb it, especially as we age.
    You can get sublingual B12 in the drugstore over the counter, typically in 500 or 1000 mcg. If you are deficient, you will see a difference shortly. I began with 500 once a day and it did the trick! Now I do anywhere from 500 to 1500 mcg per day and feel fine.

  4. Sandy

    I had gastric bypass surgery in 1999. The surgeon had me on “B-12” shots for over 10 years. Many unbearable symptoms. Doctors wanted to “bandaid” not find out why. “B-12” blood tests always showed high.
    Of course they did! No stomach, no B-12 intrinsic factor to convert cyanocobolomin to methylcobomin! When I realized this, I started on methyl-, quit cyano-. Within 6 months I was much better. However, now I have many health challenges that never would have happened had I not had the surgery or wouldn’t have been as bad had I been on methyl- from the start. This same thing killed my Mom in Sept, 2012. I was so bad off I couldn’t be with her the last year or so. Lack of methylcobolomin (for whatever reason) KILLS!

  5. Connie

    The article or the comments, NO ONE mentioned ‘HOW MUCH, MG OR WHATEVER, ARE WE SUPPOSE TO HAVE OF B-12?!
    Is it better to get it in a a shot, or are pills/capsules ok.?
    Thank you, Connie

  6. paul43

    Anyone have any more info on B-12 please?
    I know I suffer from mild depression and maybe the B-12 will help.

  7. Sara C.

    This happened to me! I thought I was getting dementia. I am 65 but have always taken a good B complex supplement and so it never occurred to me I could be deficient in any B vitamin. If it hadn’t been for my hospital-lab-director relative who suggested it, lord knows what would have happened. Not only was my short term memory truly bad (trouble remembering whether I had just brushed my teeth without feeling my toothbrush, a few times a week!) but I had a moment of confusion that terrified me. I couldn’t understand the numbers on my digital clock one night. Uh oh.
    I noticed I had poor balance, so that when closing my eyes to wash my hair in the shower, I would stagger. Considering I am active and do ballroom dancing, this made no sense. But Pat explained that people over 50 can have such difficulty absorbing B12 through the gut that only a tiny amount gets through. She suggested sublingual B12 so that it goes directly into the bloodstream. If I wasn’t deficient, it wouldn’t hurt me and if I was, it would help.
    I got some at the drugstore and within only a few days my mental confusion and other symptoms were greatly reduced, then gone. I feel like myself again, several months later. Maybe my thinning hair will reverse itself, too! I’ve since learned that B12 deficiency is greatly under-diagnosed, especially in older persons.

    • Roop

      Hello Sara,

      Hope you are having a strong memory now. One Q- For how long did you suffer from short term memory loss, because you have mentioned that you recovered within few days after taking Vit B12.

  8. Paulbyr

    My internal medicine Dr. just suggested that, since I have been taking Protonix for a long time, I should get a B12 test. I will contact her on Monday ans ask for the lab appointment.
    Thank you for this informative article!

  9. abigail

    I have been eating sprouted Quinoa in quantity and often. Began having some of the symptoms described above. My haircutter is very into healthy eating and, while we were discussing Quinoa, she went online and entered Quinoa nutrition. The information she found was that Quinoa has almost no B12 and Niacin. I cannot vouch for on-line information, but since adding B vitamins and B12 sublingual and Niacin to my diet my energy and spirits have improved.

  10. Helen M

    Oh my! Potassium? I have been taking prescription potassium since the 60s. No one has ever said anything about B12. When I was using glucophage, I knew about B12 and began supplementing with it. Then I read about certain mutations that can interfere with absorption, so about a year or two ago switched over to the methyl form.
    Apropos to another article this week in PP, I also lost my thyroid gland to cancer in 2002. Since I have anemia, it is hard to get real solid information from my thyroid tests and I have titrated my dose by intuition and hope since I began using natural thyroid a year or so ago. This is the first doctor I have had who is willing to prescribe it, but he left the dosing up to me. I have all the symptoms you mention in this article, particularly the mild cognitive impairment. We are working on the anemia, I am leaving my thyroid dose where it is, for now; however, after reading the above, will think about increasing my dose of B12. I also take the methyl form of folate. Maybe ask for testing.

  11. hjl

    Just to get followup comments.

  12. Linda C

    Where does B12 occur naturally? I assume meat since vegetarians may have low levels. Any where else?
    People’s Pharmacy response: Brewer’s yeast is another source of vitamin B12.

  13. SMB

    There was no mention of the amount of Vitamin B 12 supplement best for your daily consumption.
    It was recommended to me by my prostate oncologist to take 1,000 mcg a day.

  14. susan

    Due to stomach surgery many years ago, I have problems absorbing all vitamins. I have found that after swallowing the vitamins I drink a tablespoon of apple cider vinegar (with a cup of water), the vitamins are absorbed. Some days instead of the vinegar I take one digestive enzyme, which seems to
    work well too.

  15. Liz

    I took 10mg of Omeprazole daily for years and thanks to information on this site and consuming LOTS of milk daily I was able to wean myself off of the drug over the course of three months. I was suffering from sinus headaches that were later diagnosed as migraines, I had severe carpal tunnel symptoms and in general I was miserable. My B12 levels weren’t severely low when I started seeing my neurologist but they were low enough that my body was not happy (my B12 serum was 337). My neurologist put me on 400mg of Riboflavin for my migraines, that coupled with stopping the Omeprazole changed everything for me.
    I still have tingling and numbness in my hands when typing for a long time, but I don’t get migraines nearly as often. I don’t think the dangers of PPIs are known enough to the general public, and I scoff every time I see a Nexium OTC commercial. I still get acid reflux symptoms, but I just try to drink a big glass of milk or chew some gum and usually I can find relief. The slight discomfort from the reflux is better than the alternative.

  16. Jackie Mae H.

    I take Nexium for Barrett’s esophagus but I take liquid B complex, but I still have some of those problems

  17. MMH

    Interesting article. Could you publish information on good sources of B12?

  18. JFR

    Many years ago, I suffered burning feet and also stabbling pains over all my body. My doctor, who is a D.O., prescribed Hydroxocobalamin, (Methylcobalamine) B12 injections from a compounding pharmacy. Later, after I moved to another city, my Internal Medicine doctor said there was no need to spend all that money on that type of B12
    He said my body would convert the cynocobalamine, a less active form, to Methylocbalamine. I switched and my horrible symptoms came back with a vengeance. Obviously, I switched back to my original prescription. My symptoms ceased entirely. Obviously my body does not covert the B-12.

What Do You Think?

We invite you to share your thoughts with others, but remember that our comment section is a public forum. Please do not use your full first and last name if you want to keep details of your medical history anonymous. A first name and last initial or a pseudonym is acceptable. Advice from other commenters on this website is not a substitute for medical attention. Do not stop any medicine without checking with the prescriber. Stopping medication suddenly could result in serious harm. We expect comments to be civil in tone and language. By commenting, you agree to abide by our commenting policy and website terms & conditions. Comments that do not follow these policies will not be posted.