Vitamin B deficiency symptoms: What are the early signs of vitamin B deficiency?

Medically reviewed by Karen Berger, Pharm.D.
Licensed Pharmacist
Updated Aug 20, 2025  •  Published Jun 2, 2023
Datos Verificados
In this article:

Overview: What does vitamin B deficiency feel like?

There are eight types of vitamin B. All are water-soluble vitamins. Each type plays a different, unique, and necessary role in meeting the body’s needs. In general, people with low levels of vitamin B will feel tired, fatigued, or start showing symptoms of anemia (low red blood cell counts) like fatigue and pale skin. Many vitamin B deficiencies manifest as skin problems, particularly dry and cracked skin. Most vitamin B deficiencies cause nerve dysfunction, so a generalized vitamin B deficiency will also cause problems like poor balance, clumsiness, strange skin sensations, pain, confusion, memory lapses, and, in severe cases, psychosis and delirium.

RELATED: 9 common nutrient deficiencies in the U.S.

Key takeaways:

  • Vitamin B deficiency is a common health condition that can affect anyone regardless of age, sex, race, or ethnicity. 

  • Early signs of vitamin B deficiency include tiredness, fatigue, skin problems, and tongue swelling.

  • Serious symptoms of vitamin B deficiency, such as signs of anemia, severe alterations in mood, and severe mental changes such as psychosis, delirium, seizures, or coma, may require immediate medical attention.

  • Vitamin B deficiency has many causes depending on the deficiency type. The most common cause of generalized vitamin B deficiency is poor nutrition or food-restrictive diets. Other possible causes of vitamin B deficiencies include pernicious anemia (an autoimmune condition that prevents the body from absorbing vitamin B12), gastritis (inflammation of the stomach lining), digestive system problems such as inflammatory bowel disease or celiac disease), autoimmune disorders, genetic disorders, hormone disorders, breastfeeding, or side effects of prescription medications such as metformin or proton pump inhibitors (such as Prilosec or Nexium). You may be at risk for developing vitamin B deficiency symptoms if you have a poor or severely restricted diet, take certain medications, have certain types of gastrointestinal diseases, or drink too much alcohol.

  • Vitamin B deficiency requires a medical diagnosis.

  • Vitamin B deficiency generally requires treatment. Vitamin B deficiency symptoms typically resolve with treatment within a variable timeline depending on the deficiency type.

  • Treatment of vitamin B deficiency treatment may include dietary changes, supplements, and/or treating the underlying cause.

  • Untreated vitamin B deficiency could result in complications like anemia, malnutrition, nervous system disorders, psychiatric disorders, seizures, heart problems, and death.

Use coupons for vitamin B deficiency treatments like folic acid, pyridoxine, and biotin to save up to 80%.

What are the early signs of vitamin B deficiency?

The most common early signs of a generalized vitamin B deficiency are:

  • Tiredness or fatigue

  • Skin changes such as dry skin, cracked skin, dermatitis, or pale skin

Other vitamin B deficiency symptoms

Each type of vitamin B has different functions in the body. Symptoms will depend on which types of vitamin B are deficient in the body. These include:

Symptoms of vitamin B12 (cobalamin) deficiency:

One of the most common (and potentially severe) B vitamin deficiencies is vitamin B12 (cobalamin) deficiency. It can lead to serious complications such as vitamin B12 deficiency anemia. Symptoms of B12 deficiency may include:

  • Symptoms of anemia such as tiredness, fatigue, pale skin, clammy skin, and yellowing of the skin

  • Headache

  • Diarrhea

  • Swollen, painful tongue

  • Numbness or tingling

  • Loss of balance and coordination

  • Irritability

In severe cases, or if left untreated, symptoms may include confusion, psychosis (a disconnection from reality), and dementia (problems with memory and thinking). 

Symptoms of vitamin B9 (folic acid) deficiency:

Not enough vitamin B9 (folic acid) in the body is another common and serious vitamin B deficiency. Folate deficiency symptoms may include:

  • Symptoms of megaloblastic anemia such as fatigue and pale skin

  • Neurological symptoms such as tingling or numbness

  • Symptoms of central nervous problems such as irritability, depression, memory problems, memory loss, confusion, and dementia

  • Headache

  • Muscle weakness

  • “Beefy” red tongue

  • Shortness of breath

  • Mouth sores

Symptoms of vitamin B1 (thiamine) deficiency:

A thiamine deficiency is a severe and potentially life-threatening condition. Beriberi is a condition that may occur in people with a vitamin B1 deficiency. The most common early symptoms of B1 deficiency are:

  • Loss of appetite

  • Fatigue

  • Irritability

  • Sleep problems

  • Stomach discomfort

Symptoms of vitamin B3 (niacin) deficiency:

A niacin deficiency, called pellagra, can be a serious threat, even fatal. It is characterized by a set of three symptoms including diarrhea, skin inflammation, and dementia, more specifically:

  • Digestive system problems such as watery diarrhea, appetite loss, stomach pain, nausea, and swollen, beefy red tongue

  • Skin problems such as redness, burning, rash, and photosensitivity

  • Mental changes such as depression, anxiety, difficulty concentrating, irritability, confusion, dementia, and coma

Symptoms of vitamin B6 (pyridoxine) deficiency (uncommon):

Vitamin B6 is called pyridoxine. It is an extremely vital nutrient, but a B6 deficiency alone isn’t very common. It mainly appears in people who have other nutrient deficiencies. Symptoms include: 

  • Skin problems including cracking and scaling, particularly around the corners of the mouth

  • Swollen tongue

  • Symptoms of anemia

  • Weakened immune system

  • Infants may experience irritability, extremely acute hearing, and seizures

Symptoms of vitamin B7 (biotin) deficiency (uncommon):

A vitamin B7 (biotin) deficiencyis very uncommon. Severe biotin deficiency is serious, but it is very rare. A biotin deficiency usually causes minor symptoms such as: 

  • Skin rash

  • Cracked nails

  • Hair loss

A more severe biotin deficiency can cause other symptoms such as:

  • Seizures

  • Peripheral neuropathy

  • Depression

  • Lethargy

Symptoms of vitamin B2 (riboflavin) deficiency (rare):

A riboflavin deficiency is also a potentially serious medical condition but is extremely rare. Generally, people with riboflavin deficiencies also have deficiencies of other nutrients. In the U.S., it mainly affects people who abuse alcohol or who take birth control pills. Symptoms may include:

  • Skin problems like cracking and itching

  • Tiredness

  • Swollen throat

  • Vision problems

  • Depression

  • Hair loss

  • Liver problems

Symptoms of vitamin B5 (pantothenic acid) deficiency (rare):

A deficiency of pantothenic acid is very rare and usually experienced in people with a rare genetic disorder. Symptoms of a severe deficiency may include:

  • Tiredness

  • Headache

  • Digestive system problems such as nausea, vomiting, diarrhea, heartburn, stomach pain, and appetite loss

  • Burning hands and feet

  • Mental changes such as irritability, restlessness, and problems sleeping

Vitamin B deficiency vs. hypothyroidism

Vitamin B deficiencies can be confused with other health problems including malnourishment, anemia, lupus, Crohn’s disease, ulcerative colitis, multiple sclerosis, alcoholic liver disease, lead toxicity, and liver failure. Many of the symptoms of vitamin B deficiency are most similar to those of an underactive thyroid: skin problems, fatigue, nerve problems, low energy, anemia, and psychiatric issues. Like vitamin B deficiencies, these symptoms are often nonspecific, so it’s easy to confuse hypothyroidism with other health issues. To add to the confusion, B12 deficiency is often associated with low thyroid function.

Vitamin B deficiency Hypothyroidism
Shared symptoms
  • Low energy
  • Tiredness
  • Anemia symptoms such as fatigue, pale skin, and weakness
  • Psychiatric problems such as depression, irritability, or feeling stressed
  • Skin problems such as dry skin, brittle nails, and hair loss
  • Cognitive problems such as memory impairment, difficulty concentrating, or confusion
  • Peripheral nerve problems such as tingling skin sensations
Unique symptoms
  • Diarrhea
  • Weight loss
  • Nausea and vomiting
  • Fast heart rate
  • Swollen tongue
  • Severe central nervous system problems such as seizures, psychosis, dementia, and coma (in severe cases)
  • Constipation
  • Weight gain
  • Cold intolerance
  • Slow heart rate
  • Menstrual problems
  • Muscle pain
  • Joint pain
  • Sleep problems

RELATED: Hypothyroidism vs. hyperthyroidism: compare causes, symptoms, treatments & more

When to see a doctor for vitamin B deficiency symptoms

If any symptoms of a vitamin B deficiency are noticed, talk to a doctor for three major reasons. First, the deficiency has usually gone on for some time before symptoms appear. Second, symptoms of anemia, neurological problems, or cognitive decline should always be evaluated by a healthcare professional. Finally, many vitamin B deficiencies can cause serious and potentially chronic health issues such as nerve damage, heart problems, infections, and kidney problems. 

Healthcare providers diagnose vitamin B deficiencies from the symptoms, medical history, physical examination, and blood tests. The clinician may ask detailed questions about daily diet, prescription drugs, alcohol use, surgeries, or gastrointestinal problems like inflammatory bowel disease (IBD). Many symptoms of vitamin B deficiencies are visible so the clinician will look for these telltale signs. Blood tests will help confirm the deficiency, as well as identify other problems such as anemia. Other more extensive tests may be needed to identify a possible cause.

Complications of vitamin B deficiency

The complications of vitamin B deficiencies depend on what types of vitamin B are deficient in the body. Some vitamin B deficiencies are more health-threatening than others. In general, severe, untreated vitamin B deficiencies can lead to possible complications such as:

  • Anemia

  • Malnutrition

  • Heart problems

  • Heart failure

  • Nerve damage

  • Spinal cord degeneration

  • Debilitating neurological deficits

  • Cognitive impairment

  • Severe psychiatric disorders

  • Developmental abnormalities

  • Increased risk of stomach cancer 

  • Death

RELATED: How to absorb vitamins better

How to treat vitamin B deficiency symptoms

Vitamin B deficiencies are usually treated with high-dose prescription vitamin B supplements. In more serious cases, healthcare providers inject a high vitamin B dose directly into the body (or patients will self-inject at home, after being trained). Length of treatment will vary depending on the deficiency. If the vitamin B deficiency is due to another medical condition, that condition will also need treatment. 

After recovery, the standard treatment is to continue with supplements such as folate, biotin, pyridoxine, or multivitamins and to adopt a healthy, mixed diet that includes animal products like fish, meat, chicken, eggs, and dairy. 

Signs vitamin B deficiency is getting better

The goal for treatment of a vitamin B deficiency is to get vitamin B levels back to normal. Depending on the deficiency, this may take a few days to a few weeks or months. People without symptoms will not know they’re better until a blood test confirms that vitamin B levels are normal. People with symptoms will notice the symptoms improving, along with vitamin B levels returning to normal. Anemia and nerve damage can take months to improve, even when vitamin B levels return to normal.

Most importantly, eat a healthy and mixed diet

The best treatment for any nutrient deficiency is a healthy, varied diet. Some people may need to add over-the-counter supplements but ask for medical advice first. To avoid vitamin B deficiency, eat a diet with a variety of food sources, including: 

  • Fortified cereals, whole grain breads, or other foods

  • Animal products such as red meats, poultry, liver, eggs, seafood, and fish (especially salmon or tuna)

  • Dairy products

  • Green vegetables (especially broccoli and dark, leafy greens)

  • Beans and legumes

  • Some fruits such as bananas, avocadoes, oranges, and cantaloupe

  • Brown rice

  • Whole grains

  • Nuts and seeds (especially almonds, peanuts, and sunflower seeds)

FAQs about vitamin B deficiency symptoms

What are unusual symptoms of B deficiency?

The most common symptoms of vitamin B deficiencies are tiredness, skin problems, peripheral nerve problems, cognitive deficits, mood changes, and anemia. Some types of vitamin B deficiencies cause less expected issues, such as heart problems (vitamin B1 deficiency), a weakened immune system (vitamin B6 deficiency), or body-wide or even total hair loss (vitamin B7 deficiency).

How can I raise my B12 levels fast?

Healthcare professionals use high-dose prescription B12 supplements or intramuscular injections (injection into a muscle) to increase vitamin B12 levels rapidly.

What depletes B vitamins?

Several problems can cause vitamin B deficiencies. The number one culprit is poor diet. This may be due to food insecurity, poor food choices, or restrictive or food-avoidance diets such as a vegan diet, vegetarian diet, or some weight loss diets.

What’s next? Additional resources for people with vitamin B deficiency symptoms

Test and diagnostics

Treatments

Scientific studies and clinical trials

Hypothyroidism treatments and medications, SingleCare

Medically reviewed by Karen Berger, Pharm.D.
Licensed Pharmacist

After receiving her doctorate from the University of Pittsburgh School of Pharmacy, Karen Berger, Pharm.D., has worked in both chain and independent community pharmacies. She currently works at an independent pharmacy in New Jersey. Dr. Berger enjoys helping patients understand medical conditions and medications—both in person as a pharmacist, and online as a medical writer and reviewer.

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