When Will I Feel Better With B12?

Mushrooms are filled with vitamin B12.
Image Credit: Zakharova_Natalia/iStock/GettyImages

Vitamin B12 deficiency is fairly common, especially among older people, who tend to have more difficulty absorbing the vitamin than younger adults. B12 injections or supplements can help correct a deficiency, but there's no way to predict how long it will take for you to start feeling better.


The length of your B12 deficiency recovery depends on several different factors, including how severe your deficiency is and whether your body can absorb vitamin B12 the way it's supposed to. The best thing you can do is stick to the treatment plan your doctor or nutritionist has given you and try to stay patient through the process.

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The amount of time it takes you to feel better after beginning treatment for a vitamin B12 deficiency depends on the severity of your deficiency and how well your body absorbs the vitamin. In many cases, treatment can last weeks to months, but it's likely that you may experience some relief of symptoms even before your treatment is complete.

Vitamin B12 Deficiency

According to a report that was published in the September 2017 issue of American Family Physician, vitamin B12 deficiency affects approximately 6 percent of American adults under the age of 60 and almost 20 percent of people who are older than that.

Because vitamin B12 plays a role in so many different functions in your body, a deficiency in the vitamin can manifest in many different ways and cause a wide array of symptoms that can sometimes make it difficult to diagnose. Possible symptoms of a B12 deficiency are:

  • Fatigue and tiredness

  • Weakness

  • Constipation

  • Loss of appetite

  • Weight loss

  • Anemia

  • Numbness and tingling in the hands and feet

  • Difficulty balancing

  • Depression

  • Confusion

  • Memory loss

  • Soreness of the mouth and/or tongue


A deficiency usually develops over an extended period of time, usually months to years. The symptoms may start out mild or barely noticeable at first, but as the deficiency worsens, symptoms become more noticeable and severe.

Vitamin B12 Deficiency Recovery

Treatment for vitamin B12 deficiency usually consists of supplementation, but the type of supplement you need depends on the severity of your deficiency and what the underlying cause is. According to Harvard Health, a severe vitamin B12 deficiency can usually be corrected with either regular vitamin B12 shots or high-dose B12 pills or capsules. If your deficiency is on the milder side, an over-the-counter multivitamin or B complex supplement is usually enough to do the trick.


If you're getting B12 injections, they're usually administered by a health care professional every other day for two weeks and then monthly for three months. However, if your deficiency is so severe that you've developed neurological symptoms, like numbness and tingling in the hands and feet or difficulty balancing, then you'll be given an injection every other day until those symptoms resolve, and then once a month for two months.


Most standard B12 injections contain 1 milligram of vitamin B12, but you absorb only about 10 percent, or about 100 micrograms, of the vitamin. However, even though you absorb such a small amount, that's still almost 40 times more than the amount that you need for the entire day (which is 2.4 micrograms).


Read more:The Side Effects of Too Much Vitamin B12

A Word on Intrinsic Factor

Intrinsic factor is a protein that's secreted by the cells in the lining of your stomach. When you consume vitamin B12, either through food or supplements, intrinsic factor attaches to the vitamin and allows you to absorb it in your small intestine. You can't properly absorb vitamin B12 without intrinsic factor, no matter how much you take in. Because of this, people who don't make intrinsic factor are at a much higher risk of developing a vitamin B12 deficiency.


Treatment for vitamin B12 deficiency in people without intrinsic factor is also different from treatment for people who don't have problems with absorption. The only way to correct vitamin B12 deficiency in someone without intrinsic factor is to utilize B12 injections. The B12 from oral supplements or foods won't be properly absorbed. Because of this, it's often necessary for people who don't make intrinsic factor to get B12 injections regularly for the rest of their lives.


According to the Mayo Clinic, lack of intrinsic factor may be caused by an autoimmune disease that mistakenly attacks the cells in the stomach that make it. It can also develop as a result of gastric bypass surgery or other types of surgery on the stomach that cause physical damage to the cells in the stomach that make the protein.

Read more:Vitamin B12 Shots vs. Pills


Getting Enough B12 From Foods

Once your deficiency is corrected and supplements aren't needed anymore, it's important to make sure that you're regularly getting enough vitamin B12 from the foods that you eat so you don't develop a deficiency again.


Because B12 is a water-soluble vitamin, your body doesn't store excess amounts of it, so even if you're getting high-dose injections or taking oral supplements, your body will still use only what it needs and then get rid of the rest through your urine. That's why you need to make sure you're regularly meeting your needs.

If your deficiency was caused by something other than a lack of intrinsic factor and is now corrected, you can meet your needs by consuming B12-rich foods in adequate amounts on a daily basis. Examples of foods that are high in B12 include:

  • Beef liver
  • Clams
  • Fish
  • Beef
  • Poultry
  • Eggs
  • Dairy products (milk, yogurt and cheese)

You may have noticed that all of these foods come from animal products. This is why vegans and vegetarians have a higher risk of developing a vitamin B12 deficiency than meat eaters. If you don't eat meat or animal products, you can get some vitamin B12 from fortified foods, like cereal or enriched bread, but it's harder to meet your needs. In these cases, it might be a good idea to continue taking a supplement, just in case.




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