What happens when you lack vitamin B6?

November 17, 2025 •

3 min read

According to the NIH, while rare, vitamin B6 deficiency can lead to a range of symptoms impacting the nervous system, skin, and immune function. A severe and prolonged lack of this essential nutrient is associated with significant health issues that extend beyond minor fatigue.

Quick Summary

A lack of vitamin B6, also known as pyridoxine, can cause neurological problems like peripheral neuropathy and confusion, along with skin issues and anemia. It can also weaken the immune system and affect mood. A deficiency is often linked to other B vitamin deficiencies or underlying medical conditions.

Key Points

Neurological Problems: A lack of vitamin B6 can cause peripheral neuropathy, leading to numbness, tingling, and a 'pins-and-needles' sensation in the hands and feet.
Mood and Cognitive Changes: Deficiency can impact neurotransmitter synthesis, resulting in mood issues like depression, irritability, and confusion.
Skin and Oral Issues: Seborrheic dermatitis, cheilosis (cracked lips), and glossitis (a swollen, red tongue) are common dermatological symptoms of low B6.
Anemia: B6 is essential for hemoglobin production; therefore, a deficiency can lead to microcytic anemia, causing fatigue and weakness.
Weakened Immune System: A lack of B6 impairs immune function by reducing the production of antibodies and white blood cells, increasing susceptibility to infections.
Rare in Healthy Individuals: While a pure dietary deficiency is uncommon, it can occur in individuals with malabsorption issues, chronic alcohol dependence, kidney disease, or those taking specific medications.
Treatable with Supplements: Mild to moderate deficiencies are typically corrected with dietary changes and B6 supplements under medical guidance.

What is Vitamin B6 and Why is it Important?

Vitamin B6, or pyridoxine, is a crucial water-soluble vitamin involved in more than 100 enzyme reactions in the human body. Its active coenzyme forms, pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP), are essential for protein metabolism, red blood cell formation, neurotransmitter synthesis, and immune function. Because it is water-soluble, the body does not store large amounts, making a consistent daily intake necessary. While overt deficiency is rare in developed countries, suboptimal levels can exist, especially in certain at-risk populations.

The Role of Vitamin B6 in the Body

Amino acid metabolism: As a key coenzyme, B6 facilitates the metabolism of amino acids, the building blocks of proteins.
Brain function: B6 is vital for the synthesis of neurotransmitters, such as serotonin, dopamine, and GABA, which regulate mood, behavior, and brain energy use.
Immune function: It is necessary for the production of antibodies and white blood cells, which are crucial for fighting off infections.
Hemoglobin formation: B6 is required for making hemoglobin, the protein in red blood cells that carries oxygen throughout the body. A lack of B6 can lead to anemia.
Cardiovascular health: It helps regulate homocysteine levels, an amino acid that, in high amounts, can increase the risk of heart disease.

Symptoms of a Vitamin B6 Deficiency

Symptoms of a vitamin B6 deficiency can range from mild to severe, often affecting the skin, nervous system, and overall energy levels. In many cases, it is accompanied by other B vitamin deficiencies, such as folic acid and vitamin B12. Recognizing these symptoms is the first step toward diagnosis and treatment.

Neurological and Psychological Symptoms

Peripheral Neuropathy: Deficiency can cause nerve damage resulting in numbness, tingling, and a "pins-and-needles" sensation.
Confusion and Cognitive Issues: Low B6 can impact brain function, leading to confusion and difficulty concentrating.
Depression and Irritability: A deficiency can cause or worsen mood disorders due to B6's role in synthesizing neurotransmitters.
Seizures: In severe cases, particularly in infants, deficiency can cause seizures.

Dermatological and Oral Symptoms

Seborrheic Dermatitis: A red, scaly rash may appear on the scalp, face, and chest.
Cheilosis: Scaly lips and painful cracks at the corners of the mouth can occur.
Glossitis: The tongue may become swollen, smooth, and red.

Other Systemic Effects

Anemia: A lack of B6 can lead to microcytic anemia, characterized by small, pale red blood cells, causing fatigue and weakness.
Weakened Immune Function: B6 deficiency impairs the production of immune cells, increasing susceptibility to infections.
Fatigue and Low Energy: Due to its role in energy metabolism and red blood cell formation, B6 deficiency often causes persistent fatigue.

Causes of Vitamin B6 Deficiency

While poor diet can contribute, deficiency is more commonly a secondary result of other underlying conditions.

Primary Causes

Poor Dietary Intake: Severely restricted diets or extensive food processing can lead to low intake.
Alcohol Dependence: Excessive alcohol use interferes with B6 use, often leading to low levels.

Secondary Medical Causes

Malabsorption Disorders: Conditions like celiac disease or bariatric surgery can impair B6 absorption.
Kidney Disease: Impaired renal function increases the risk due to increased B6 clearance.
Autoimmune Disorders: Conditions like rheumatoid arthritis increase B6 consumption.
Medications: Certain drugs, including some anticonvulsants and isoniazid, can interfere with B6 metabolism.

A Comparison of Deficiency and Toxicity

While B6 deficiency is a concern, excessive intake, typically from high-dose supplements, can also cause issues. The table below contrasts the key characteristics.


Feature	Vitamin B6 Deficiency	Vitamin B6 Toxicity (from supplements)
Causes	Poor diet, alcohol dependence, medications, malabsorption issues, kidney disease	Chronic high-dose supplementation (>100 mg/day)
Neurological Symptoms	Peripheral neuropathy, confusion, depression, seizures	Progressive sensory neuropathy, ataxia, numbness
Dermatological Symptoms	Seborrheic dermatitis, cheilosis, glossitis	Painful skin lesions, photosensitivity
Impact on Immune System	Weakened immune response	Not typically associated with immune suppression
Other Effects	Anemia, fatigue, low energy	Gastrointestinal issues
Treatment	B6 supplementation, dietary changes, addressing underlying causes	Discontinuation of high-dose supplements

Conclusion: Preventing Vitamin B6 Deficiency

A balanced diet is the best prevention, including foods like fish, poultry, beef liver, chickpeas, and fortified cereals. Individuals with risk factors may need monitoring and supplementation under medical supervision. Consulting a healthcare professional for diagnosis and treatment is crucial if a deficiency is suspected, as early intervention can prevent severe complications.

Frequently Asked Questions

The initial signs of a vitamin B6 deficiency often include fatigue, skin issues like a scaly rash (seborrheic dermatitis), a sore tongue, and potential mood changes such as irritability or depression.

A vitamin B6 deficiency is primarily diagnosed through a clinical evaluation of symptoms, a review of medical history, and sometimes blood tests to measure the level of pyridoxal 5'-phosphate (PLP), the active form of B6 in the blood.

Key causes include alcohol use disorder, malabsorption syndromes (like celiac or Crohn's disease), kidney failure, autoimmune disorders, and the use of certain medications, such as isoniazid.

Excellent food sources of vitamin B6 include chickpeas, beef liver, tuna, salmon, chicken breast, potatoes, bananas, and fortified cereals.

Yes, a deficiency can cause peripheral neuropathy, a type of nerve damage that results in numbness, tingling, and pain in the hands and feet.

Yes, vitamin B6 is crucial for the synthesis of mood-regulating neurotransmitters like serotonin and dopamine, so a deficiency can contribute to or exacerbate depression and anxiety.

Treatment involves increasing vitamin B6 intake, typically through oral supplements. The dosage and duration depend on the severity of the deficiency and any underlying causes.

While overt dietary deficiencies are uncommon in the general healthy population, marginal B6 status can occur, particularly in individuals with chronic health conditions, alcohol dependence, or specific medication use.