B12 supplements can start showing effects in days to weeks, with energy/fatigue improvements often noticed within 2-4 weeks, but full restoration can take months, especially with severe deficiencies, as your body needs time to absorb and build up stores. Injections work much faster (days) than oral tablets, while neurological symptom recovery (tingling, memory) might lag, sometimes taking months, though initial improvements can start in weeks.
It may take a few weeks before your vitamin B12 levels and symptoms (such as extreme tiredness or lack of energy) start to improve. If you have hydroxocobalamin injections to boost your vitamin B12 levels at the start of treatment, the cyanocobalamin tablets may start to work within a few days.
The effects of B12 shots can be felt within 24 to 72 hours, depending on the individual's current B12 levels and overall health. People who are deficient in B12 often notice an immediate boost in energy, mental clarity, and mood after their first injection.
Whereas vitamin B12 injections can start to work immediately, if you have a vitamin deficiency and start taking supplements based on medical advice, it can take up to a few weeks before your low levels start to improve.
Vitamin B12 deficiency symptoms develop gradually and include extreme fatigue, pale skin, shortness of breath, headaches, and nerve issues like numbness or tingling in hands/feet, plus cognitive problems such as memory loss and confusion, often linked to anemia but also affecting nerves and brain function, requiring medical diagnosis and treatment.
Overview. Vitamin B-12 is a vitamin the body uses to make and support healthy nerve cells. It's also used to make healthy red blood cells and the genetic material inside cells called DNA.
Lane recommends waiting at least 60 minutes between consuming coffee and supplements—especially for iron, magnesium, and B12.
B12 is a key nutrient for nervous system health. It is important for producing serotonin and dopamine, which are mood-enhancing neurotransmitters. As a result, vitamin B12 can help to prevent and treat depression and anxiety. It can improve focus and memory as well.
Some B12 supplements promise an instant energy boost. But that's often because they're packed with artificial stimulants. B12 isn't producing these on-demand results.
Vitamin B12 deficiency anaemia is usually treated with injections of vitamin B12, called hydroxocobalamin. At first, you'll have these injections every other day for 2 weeks or until your symptoms have started improving. Your GP or nurse will give the injections.
Individuals experiencing a deficiency often report feeling unusually tired or weak, even after adequate sleep. This symptom arises because a lack of B12 impairs the production of red blood cells, leading to fewer cells to transport oxygen throughout the body.
Helps Improve Sleep Patterns
Vitamin B12 is a major factor in the tryptophan production process. B12 injections can help you go from restless nights to getting a good night sleep.
In fact, some studies have even suggested the opposite. For instance, one study noted that individuals who regularly took vitamin B12 supplements gained between 2.5 to 17 fewer pounds (1.2 to 7.7 kg) over a decade than those who didn't supplement.
Which vitamins and minerals can help with tiredness and fatigue?
It works by increasing your levels of vitamin B12 so that you can make red blood cells that work properly to carry oxygen around your body. This helps to reduce symptoms such as tiredness and lack of energy.
These symptoms seem to fall into several clinically separate categories: slow cerebration; confusion; memory changes; delirium, with or without hallucinations and/or delusions; depression; acute psychotic states; and (more rarely) reversible manic and schizophreniform states.
The foods highest in Vitamin B12 are animal products, with clams and liver (beef, lamb) being exceptionally rich sources, often providing several hundred percent of the daily value in a single serving, alongside seafood like mussels, sardines, and salmon, dairy, eggs, and fortified cereals and nutritional yeast for vegans.
Vitamins B9 and B12 are both thought to treat symptoms of anxiety. Folic acid has many uses in the body, and a vitamin B9 deficiency has been linked to higher levels of anxiety and depression. When taken in conjunction with B12, these B super-vitamins help metabolize serotonin, which is important for mood regulation.
Taking certain medications: Certain medications can cause low levels of vitamin B12 in your body, including metformin, proton pump inhibitors, H2 blockers and oral birth control pills. Having Sjögren's syndrome: People with Sjögren's syndrome are more likely to have vitamin B12 deficiency.
Conclusions: Coffee consumption was associated with reduced circulating B-vitamin concentrations. The observed effect profiles indicated that coffee consumption preferentially affected the upper, but not the lower, part of the B-vitamin concentration distributions.
B12, vitamin B-12. supplementation can effectively reduce uric acid concentrations or can reduce the risk of hyperuricemia.
B12 deficiency can trigger specific food cravings, most notably for meat, fish, or eggs, as the body seeks animal-based sources to replenish the vitamin, especially in those on vegetarian/vegan diets or older adults. While cravings for sugary or salty foods can also signal general B-vitamin issues, the distinct urge for protein-rich animal products is a key indicator, but professional testing is crucial for confirmation.
Vitamin B12 is required for the development, myelination, and function of the central nervous system; healthy red blood cell formation; and DNA synthesis [1,4,5]. Vitamin B12 functions as a cofactor for two enzymes, methionine synthase and L-methylmalonyl-CoA mutase [1-3,5].
Vitamin B12 deficiency can also cause symptoms that affect your brain and nervous system (neurological symptoms), including:
While Vitamin B12 is generally safe, potential disadvantages (side effects) can occur, especially with high doses or injections, including headaches, nausea, diarrhea, weakness, skin issues (rash, itching), and rarely, more serious heart or allergic reactions (like anaphylaxis), though toxicity from oral intake is rare as excess is usually excreted. Conversely, a deficiency can cause serious problems like irreversible nerve damage, memory loss, fatigue, infertility, and increased risk of certain cancers, making proper intake crucial.