How long does vitamin B12 last in your system?

Vitamin B12 stays in your system for a long time because your body stores significant amounts in the liver, potentially for years, even if you stop consuming it. In your blood, it has a half-life of about 6 days, meaning half is used or excreted, but substantial reserves in the liver mean you can go years without dietary intake before developing deficiency symptoms.

How long does it take to get vitamin B12 out of your system?

If you don't have a vitamin B12 deficiency, most of the vitamin B12 you get through your injection will be absorbed and eliminated quickly through your urine. This accounts for the people in the research that found 98% of their injected vitamin B12 in their urine 48 hours after it was administered.

What are the worst symptoms of B12 deficiency?

The worst symptoms of B12 deficiency involve severe neurological and cognitive damage, including paralysis, dementia, psychosis, severe memory loss, persistent numbness/tingling (neuropathy), balance issues (ataxia), incontinence (bowel/bladder), and vision loss, which can become permanent if untreated, alongside extreme fatigue, depression, and heart problems from anemia. These severe effects often stem from nerve damage (peripheral neuropathy) and spinal cord degeneration.
 

What happens to your body when you take vitamin B12 every day?

Taking vitamin B12 daily is generally safe for most people, as it's water-soluble and excess is flushed out in urine, but very high doses, especially via injections, might cause headaches, nausea, tingling, or diarrhea, with some rare links to acne or even increased cancer risk, so always check with a doctor before starting high doses to ensure you need them and to rule out interactions.
 

How long until B12 wears off?

Typically, you'll enjoy the benefits for about one to two weeks. But the exact duration depends on your body's needs, how deficient you are, and your overall lifestyle. Your current B12 levels, metabolism, diet, and how often you receive injections all play a role.

How Long to Recover from Vitamin B12 Deficiency ❓

When should you stop taking vitamin B12?

Although it's less common, people with vitamin B12 deficiency caused by a prolonged poor diet may be advised to stop taking the tablets once their vitamin B12 levels have returned to normal and their diet has improved.

Can vitamin B12 cause a rash?

talk to a doctor or healthcare professional if you are given or are taking vitamin B12 and you develop allergic skin reactions such as a rash or hives.

What do you crave when your B12 is low?

B12 deficiency can trigger cravings, particularly for nutrient-dense animal products like meat, fish, and eggs, as the body seeks the vitamin, though some link it to general sugar or carbohydrate cravings due to its role in mood/energy via serotonin. These urges, especially persistent ones for specific foods, can signal a shortage, but clinical testing is needed for confirmation as cravings can also stem from habits or emotions. Addressing B12 deficiency involves supplements or fortified foods, alongside a balanced diet rich in animal products and fortified options.
 

Is there any downside to taking vitamin B12?

Safety and side effects

Taking doses of vitamin B-12 might cause: Headache. Nausea. Diarrhea.

What organ does vitamin B12 affect?

Vitamin B12 does a lot of important things for your body. It helps create your DNA and red blood cells, for example. Your body also needs B12 for the development of your central nervous system (your brain and spinal cord).

What are the facial signs of B12 deficiency?

Cutaneous manifestations associated with vitamin B12 deficiency are skin hyperpigmentation, vitiligo, angular stomatitis, and hair changes. A diagnosis of vitamin B12 deficiency is often overlooked in its early stages because these signs are not specific to vitamin B12 deficiency alone.

How can I check my B12 level at home?

Yes, you can easily do a Vitamin B12 test at home using kits from various providers like Complement, Quest Diagnostics, Labcorp, and others, which involve a simple finger-prick blood sample or sometimes a urine sample, mailed to a lab for analysis, with results delivered online, often with recommendations for supplementation if needed, though some tests like Quest Diagnostics may involve scheduling a mobile phlebotomist. 

What food is highest in B12?

The foods highest in Vitamin B12 are organ meats (like liver and kidney) and shellfish (especially clams), followed by fatty fish (salmon, sardines, trout), meat, eggs, and dairy; fortified cereals and nutritional yeast are excellent options for vegetarians/vegans. A 3-ounce serving of clams can provide thousands of percent of your daily needs, while beef liver is also extremely concentrated in B12.
 

What does it feel like when you have too much B12?

Too much vitamin B12 usually causes mild symptoms like headaches, nausea, diarrhea, weakness, or tingling in hands/feet, but serious issues are rare and often linked to injections or underlying conditions, with signs like severe anxiety, heart palpitations, difficulty breathing, or acne, requiring a doctor's visit as high levels can sometimes signal other health problems.
 

What are the mental symptoms of B12 deficiency?

Vitamin B12 deficiency can also cause symptoms that affect your brain and nervous system (neurological symptoms), including: numbness. muscle weakness. psychological problems, which can range from mild depression or anxiety, to confusion and dementia.

Will side effects of B12 go away?

Some side effects of cyanocobalamin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

What to avoid when taking vitamin B12?

When taking B12, you should be cautious with stomach acid reducers (PPIs, H2 blockers), diabetes drugs like Metformin, certain antiseizure meds (Phenytoin), gout meds (Colchicine), and high doses of Vitamin C, as they can impair B12 absorption, and be aware that high Folic Acid can mask B12 deficiency, while excessive alcohol also depletes it. 

What kind of B12 is best for seniors?

Active B12 is generally considered to be the best form of B12 for seniors for several reasons. Metabolically active forms of B12 such as methylcobalamin and adenocobalamin require no further conversion in the body.

What happens to your body when you start taking vitamin B12?

Taking Vitamin B12 supports nerve and blood cell health, aids in DNA synthesis, boosts energy by converting food to fuel, improves mood and brain function, and helps prevent anemia, with excess amounts generally flushed out in urine, though very high doses can rarely cause side effects like headaches or tingling. It's crucial for red blood cell formation and nervous system health, especially for vegetarians, older adults, and those with absorption issues.
 

Which fruit is B12 rich?

Apples and bananas help improve gut health, supporting better B12 absorption. Some fortified fruit juices (like orange juice) may include added B12.

How do I feel if B12 is low?

B12 deficiency feels like overwhelming fatigue, weakness, and "brain fog," along with neurological symptoms like numbness, tingling (pins and needles) in hands/feet, balance problems, and memory issues, plus physical signs like a sore tongue, pale skin, shortness of breath, and mood changes (depression, irritability). Because symptoms develop slowly and can mimic other conditions, diagnosis usually requires a blood test, and early treatment is crucial to prevent permanent nerve damage.
 

Is 2 eggs a day enough B12?

Yes, eating two eggs a day provides a significant amount of vitamin B12, often covering a good portion (around 20-40%) of the recommended daily intake for most adults (2.4 mcg), with the yolk containing more easily absorbed B12, making eggs a great dietary source, but for those with deficiencies, other animal products or fortified foods are needed for complete coverage. 

What does B12 do to your skin?

B12 is essential for cell reproduction and renewal. It supports the production of new, healthy skin cells, which helps maintain a smooth, youthful complexion. By aiding in DNA synthesis, B12 ensures that skin cells regenerate efficiently, reducing the appearance of dullness and uneven texture.

What does a B12 allergy look like?

It is possible to be allergic to vitamin B12, especially if you have a known allergy to cobalt. Allergic reaction symptoms can include skin rashes, itching, and swelling. If you suspect an allergy, consult your healthcare provider for advice and alternative options.

What are the red flags of B12 deficiency?

Warning signs of vitamin B12 deficiency include extreme fatigue, pale or yellowish skin, nerve issues like tingling/numbness, mood changes (depression, confusion), a sore/inflamed tongue, mouth ulcers, weakness, balance problems, memory issues, headaches, and shortness of breath, with symptoms developing slowly and worsening over time, potentially causing irreversible nerve damage if untreated.