B12 deficiency causes many symptoms that show up slowly over time. The most common signs include feeling very tired, having pale or yellow skin, feeling dizzy, and noticing tingling in your hands and feet. You might also have trouble thinking clearly or remembering things. These symptoms happen because your body needs B12 to make healthy blood cells and keep your nerves working right.
This article will walk you through every symptom of B12 deficiency. You’ll learn what to watch for, why these symptoms happen, and when you should talk to your doctor. By the end, you’ll know exactly how to spot the warning signs and take action.
Why B12 Matters for Your Body
Vitamin B12 is a key nutrient your body can’t make on its own. You get it from foods like meat, fish, eggs, milk, and cheese. Your body uses B12 for three big jobs:
- Making red blood cells that carry oxygen everywhere
- Keeping your nerves healthy and sending messages through your body
- Building DNA in every cell you have
Without enough B12, your body makes red blood cells that are too big and don’t work well. This means less oxygen gets to your muscles and brain. That’s why you feel tired and foggy.
Your liver stores B12 for a long time. It can take 2 to 5 years before you see signs of B12 deficiency if you stop getting enough. But once symptoms start, they get worse if you don’t fix the problem.
Early Warning Signs of B12 Deficiency
The first symptoms are easy to miss. Many people think they’re just tired from being busy. But these early signs matter because catching B12 deficiency early stops bigger problems later.
Feeling Tired All the Time
Fatigue is one of the first signs of B12 deficiency. You might sleep eight hours but still wake up exhausted. Or you need a nap every afternoon even when you used to have energy.
This happens because your cells need B12 to work right. When B12 is low, your body can’t make enough healthy red blood cells. Fewer red blood cells mean less oxygen going to your muscles and organs. Without oxygen, your body struggles to make energy.
The tired feeling from B12 deficiency is different from normal tiredness. Rest doesn’t fix it. You might feel worn out even after a full weekend off.
Pale or Yellow Skin
Your skin color can tell you a lot about your B12 levels. Low B12 can make your skin look pale because you don’t have enough healthy red blood cells. You might notice this most on your face, palms, or inside your eyelids.
Some people also get a yellow tint to their skin. This happens because B12 deficiency causes a condition called jaundice, which makes your skin and the whites of your eyes look yellow. The yellow color comes from bilirubin, a chemical that builds up when red blood cells break down too fast.
Feeling Dizzy or Short of Breath
When you don’t have enough red blood cells, your heart has to work harder. You might notice:
- Getting dizzy when you stand up
- Feeling out of breath climbing stairs
- Your heart beating fast for no reason
- Needing to sit down after light activity
Rapid breathing, shortness of breath, and dizziness are common symptoms that show your body isn’t getting enough oxygen.
Nerve and Brain Symptoms
B12 doesn’t just affect your blood. It’s also critical for your nervous system. Without enough B12, you can develop problems with your nerves, causing strange sensations like tingling, numbness, or even feeling like electricity is running through your body.
Tingling and Numbness
One of the most common nerve symptoms is a “pins and needles” feeling. You might notice numbness or tingling in your hands and feet. Some people say it feels like bugs crawling on their skin or like their feet fell asleep.
This happens because B12 is needed to make myelin, which protects your nerve cells. Without enough myelin, nerves can’t send signals correctly. The feelings usually start in your feet and legs first, then move to your hands.
If you ignore these symptoms, they can get worse. The nerve damage might become permanent if B12 stays low for too long.
Trouble Walking and Balance Problems
As B12 deficiency gets worse, it can affect how you move. You might:
- Feel unsteady on your feet
- Have trouble walking in a straight line
- Lose your balance more often
- Feel like your legs are weak
Problems with balance and coordination are neurological symptoms of B12 deficiency. This happens because B12 damage affects parts of your spinal cord that control movement. Older adults are especially at risk for falls when they have low B12.
Memory Problems and Brain Fog
B12 keeps your brain working sharp. When levels drop, you might notice:
- Forgetting words or names
- Having trouble focusing on tasks
- Feeling confused or “foggy”
- Taking longer to think through problems
Low B12 levels can make you feel foggy-headed and have difficulty concentrating and completing tasks. Some people worry they’re getting dementia, but it might just be low B12.
Doctors have mistaken B12 deficiency for Alzheimer’s in elderly patients because the symptoms look so similar. The good news? Studies show mental problems from low B12 can improve with treatment.
Mouth and Tongue Changes
Your mouth can show clear signs of B12 deficiency. These symptoms are so specific that dentists sometimes spot B12 problems before doctors do.
Red, Sore Tongue
Up to 25% of people with B12 deficiency develop glossitis, which starts as bright red patches on the tongue. The medical term is “beefy red tongue” because of how it looks.
Your tongue might:
- Turn bright red or dark pink
- Feel smooth instead of bumpy
- Hurt or burn, especially when you eat
- Swell up and feel thick
Some people lose the little bumps on their tongues, especially around the edges. These bumps hold your taste buds, so you might also notice food doesn’t taste as good.
Mouth Ulcers and Sores
Mouth ulcers and a sore tongue are common symptoms of B12 deficiency. These sores can make it painful to eat, brush your teeth, or talk. They usually heal when you start getting enough B12 again.
Mood and Mental Health Symptoms
B12 affects your brain chemistry. Low levels can change how you feel emotionally.
Depression and Anxiety
Studies show people with depression often have lower B12 levels. Low B12 causes high levels of a chemical called homocysteine. Too much homocysteine can lead to depression by damaging brain cells.
You might notice:
- Feeling sad or hopeless
- Losing interest in things you used to enjoy
- Feeling more worried or anxious than usual
- Having mood swings
Psychological problems from B12 deficiency can range from mild depression or anxiety to confusion. In severe cases, people can even have paranoia or delusions.
Irritability and Mood Changes
Small things might upset you more than they used to. You might feel grumpy, short-tempered, or emotional for no clear reason. These mood changes happen because your brain needs B12 to make chemicals that control your emotions.
Digestive System Symptoms
B12 deficiency doesn’t just affect your blood and nerves. It can also upset your stomach and digestion.
Low B12 can cause diarrhea, nausea, constipation, bloating, and gas. These symptoms happen because your digestive tract has fast-growing cells that need B12 to work right.
You might also:
- Lose your appetite
- Feel sick after eating
- Have indigestion or heartburn
- Lose weight without trying
Less Common But Serious Symptoms
Some B12 deficiency symptoms are rare but need quick medical attention.
Vision Problems
A rare condition from B12 deficiency is optic neuropathy, which damages the nerve that sends information from your eye to your brain. This can cause:
- Blurry or dim vision
- Blind spots
- Trouble seeing colors
- Gradual vision loss
Less than 1% of people with B12 deficiency get optic neuropathy, but it’s serious if it happens.
Fast or Irregular Heartbeat
Heart palpitations are a symptom of B12 deficiency. Your heart beats faster to try to pump more blood when you don’t have enough red blood cells. You might feel:
- Your heart racing or pounding
- Skipped heartbeats
- Fluttering in your chest
Headaches
Headaches are among the most commonly reported symptoms of B12 deficiency in both adults and kids. One study found that people with the highest B12 levels were 80% less likely to have migraines compared to those with the lowest levels.
How B12 Deficiency Develops Over Time
B12 deficiency happens in stages. Understanding these stages helps you catch problems early.
Stage 1: Low Blood Levels
In the first stage, you have low B12 in your blood but no symptoms yet. A blood test would show the problem, but you’d feel completely normal. This is the best time to fix it.
Stage 2: Low Cell Levels
Your cells start running out of B12. You still might not notice anything wrong, but your body is starting to struggle.
Stage 3: Early Symptoms
You develop neurological and psychological symptoms like confusion, mood swings, trouble walking or talking, and irritability. Blood tests show higher levels of certain chemicals that signal B12 problems.
Stage 4: Severe Deficiency
You develop macrocytic anemia, where your red blood cells are very large and don’t work properly. You usually feel tired and weak. If not treated, nerve damage can become permanent.
Who Gets B12 Deficiency?
Anyone can develop B12 deficiency, but some people have higher risk.
Age
About 6% of people younger than 60 have B12 deficiency, but nearly 20% of those older than 60 are deficient. Older adults make less stomach acid, which you need to absorb B12 from food. For more information on how methylated B12 can help with specific conditions, explore our detailed guide.
Diet
Vegetarians and vegans are at high risk. B12 only comes from meat, eggs, poultry, dairy products, and other animal foods. If you don’t eat animal products and don’t take supplements, you’ll eventually become deficient. Learn more about methylated B12 for vegans on our website.
Medical Conditions
Several health problems make it hard to absorb B12:
- Pernicious anemia: Your immune system attacks cells that help absorb B12
- Crohn’s disease or celiac disease: These damage your intestines
- H. pylori infection: This bacteria can hurt your stomach lining
- Type 1 diabetes: Often linked with absorption problems
Medications
Taking metformin for more than four months or proton pump inhibitors for more than 12 months increases your risk. These medicines make it harder for your body to absorb B12.
Surgery
Weight loss surgery or stomach removal makes B12 deficiency very common. The surgery removes or bypasses parts of your digestive system that absorb B12.
Testing for B12 Deficiency
If you have symptoms, your doctor will run tests to check your B12 levels.
Blood Tests
The main test measures B12 in your blood. Normal levels are usually between 200 and 900 picograms per milliliter. If your level is below 200, you’re considered deficient.
Your doctor might also check:
- Complete blood count: Shows if your red blood cells are too big
- Methylmalonic acid (MMA): Goes up when B12 is low
- Homocysteine: Another chemical that rises with B12 deficiency
When to See a Doctor
You should see a doctor if you’re experiencing symptoms of B12 deficiency. Don’t wait until symptoms get worse. Some problems caused by B12 deficiency can become irreversible if left untreated.
See your doctor right away if you have:
- Severe fatigue that doesn’t improve with rest
- Numbness or tingling that’s getting worse
- Memory problems or confusion
- Trouble walking or keeping your balance
- Vision changes
- Chest pain or irregular heartbeat
How to Fix B12 Deficiency
The good news? B12 deficiency is easy to treat once you know you have it.
B12 Supplements
For mild deficiency, oral B12 supplements of 1 to 2 mg daily are as effective as injections. You can buy B12 supplements at any drugstore. Look for methylcobalamin or cyanocobalamin on the label.
Methylated B12 is the best form because your body can use it right away without converting it. This is especially important if you have trouble absorbing regular B12. To understand how to take methylated B12 for maximum absorption, visit our guide.
B12 Injections
People with very low levels or nerve damage usually get B12 shots. These injections bypass your digestive system and go straight into your muscle. You might need shots daily or weekly at first, then monthly for life.
Dietary Changes
Eating more B12-rich foods helps prevent deficiency:
- Beef liver: One of the richest sources
- Clams and oysters: Very high in B12
- Fish: Especially salmon and tuna
- Meat: Beef, chicken, and pork
- Eggs and dairy: Milk, cheese, and yogurt
- Fortified foods: Some cereals and plant milks have added B12
How Long Recovery Takes
Improvement in symptoms typically occurs within a few weeks to a few months with appropriate treatment. Many people feel better within days of starting treatment. One study showed complete resolution of tongue symptoms after just 3 days of getting B12.
However, nerve damage takes longer to heal. Some symptoms might never fully go away if you had severe deficiency for a long time. That’s why catching it early matters so much.
Explore the benefits of methylated B12 and learn how methylated B12 helps with fatigue to understand why this form is so effective.
Preventing B12 Deficiency
Prevention is easier than treatment. Here’s how to keep your B12 levels healthy:
Eat a Balanced Diet
Include B12-rich foods in your meals regularly. If you’re vegetarian or vegan, eat fortified cereals, nutritional yeast, or plant-based milks with added B12.
Take Supplements If Needed
People over 50, vegans, and those with absorption problems should take daily B12 supplements. The recommended daily amount for adults is 2.4 micrograms.
Get Regular Check-ups
If you’re at high risk, ask your doctor to check your B12 levels during yearly exams. This helps catch problems before symptoms start.
Know Your Medications
If you take metformin, proton pump inhibitors, or H2 blockers long-term, talk to your doctor about B12 testing.
Common Questions About B12 Deficiency Symptoms
Can you have B12 deficiency without anemia?
Yes. Studies show people can have neurologic symptoms or psychiatric problems from B12 deficiency without having anemia or enlarged red blood cells. This is why doctors sometimes miss the diagnosis.
Do symptoms go away completely?
Most symptoms improve with treatment. Some symptoms, especially nerve-related ones like numbness and tingling, may not go away even with treatment if the deficiency was severe and lasted a long time.
How quickly do symptoms develop?
B12 deficiency most often begins slowly over months to years. Because your liver stores so much B12, it may take 3 to 5 years after deficiency begins before you notice symptoms.
Can B12 deficiency cause permanent damage?
Yes. B12 deficiency may cause serious complications like problems with your brain or nerves that may be permanent. This is why early diagnosis and treatment are so important.
Final Thoughts
B12 deficiency causes many symptoms that develop slowly over time. The most common signs include extreme tiredness, pale or yellow skin, tingling in your hands and feet, and trouble thinking clearly. Your tongue might turn red and sore, and you might feel depressed or anxious.
These symptoms happen because your body needs B12 to make healthy blood cells and protect your nerves. Without enough B12, your cells can’t work properly. The good news is that B12 deficiency is easy to fix once you catch it. Supplements, dietary changes, or B12 shots can bring your levels back to normal.
Don’t ignore the warning signs. If you notice symptoms of B12 deficiency, talk to your doctor about getting tested. Early treatment prevents permanent nerve damage and helps you feel better fast. Visit our shop to find high-quality methylated B12 supplements that your body can absorb easily.
Taking care of your B12 levels is one of the simplest ways to protect your health and keep your energy up. Whether through food, supplements, or medical treatment, make sure you’re getting enough of this vital nutrient.