What Happens if B6 is Too Low?

November 18, 2025 •

3 min read

According to the National Institutes of Health, vitamin B6 deficiency is uncommon in the United States, yet individuals with certain health conditions or poor diet are at a higher risk. When B6 is too low, it can lead to a range of mild to severe symptoms, impacting everything from your skin to your neurological function.

Quick Summary

A lack of vitamin B6, or pyridoxine, can cause neurological, dermatological, and psychological issues. Symptoms range from skin rashes and anemia to confusion and nerve damage, with more severe effects possible over time. Various factors, including diet, medication, and underlying medical conditions, can contribute to the deficiency.

Key Points

Symptom Spectrum: Low B6 levels can cause a range of issues, from skin rashes and a sore tongue to neurological problems like numbness, confusion, and seizures.
Multiple Causes: Deficiency is not always due to a poor diet; it can be caused by medications, alcohol use, and underlying health conditions such as kidney disease or malabsorption issues.
Neurological Impact: A severe lack of B6 can lead to peripheral neuropathy, depression, confusion, and, in infants, convulsions.
Anemia Risk: B6 is necessary for making hemoglobin, and a deficiency can result in a form of anemia that causes fatigue and weakness.
Treatment is Effective: Addressing a B6 deficiency typically involves dietary changes and, more commonly, oral supplements. Diagnosis is usually based on clinical findings and plasma level tests.

The Essential Role of Vitamin B6

Vitamin B6, or pyridoxine, is a water-soluble vitamin involved in over 100 enzymatic reactions in the body. It is critical for the synthesis of neurotransmitters that regulate mood and brain function, the production of hemoglobin for red blood cells, and the maintenance of a healthy nervous and immune system. Given its extensive role, a deficit can have far-reaching consequences throughout the body.

Key Signs and Symptoms of Low B6

When B6 levels drop, the body can signal the issue through a variety of symptoms, which may progress from mild to more severe if left untreated.

Neurological and Psychological Effects

Peripheral neuropathy: One of the most common signs, this condition causes numbness, tingling, and pain, often described as 'pins and needles,' in the hands and feet. This can lead to balance problems and difficulty walking.
Mood changes: Low B6 is linked to psychological issues like depression, confusion, and irritability. This is tied to its role in synthesizing neurotransmitters such as serotonin and GABA.
Seizures: In severe cases, especially in infants, very low B6 can trigger convulsions. These seizures may be resistant to conventional antiseizure medications.

Dermatological and Oral Manifestations

Dermatitis: An eczema-like or greasy, scaly rash can develop, particularly on the face, scalp, and upper chest. This may appear red and itchy.
Cheilosis and Glossitis: The lips may become scaly and cracked at the corners, a condition known as cheilosis, while the tongue may swell, become sore, and turn red, a symptom called glossitis.

Immune and Hematological Issues

Anemia: B6 is essential for producing hemoglobin, which carries oxygen in red blood cells. A deficiency can lead to microcytic anemia, causing small, pale red blood cells. This results in fatigue and weakness.
Weakened immune system: Adequate B6 levels are required for producing antibodies and immune cells. Low levels can compromise immune function, leaving the body vulnerable to infections.

Causes of B6 Deficiency

While dietary intake is a factor, most cases of B6 deficiency result from underlying health conditions or medication use rather than a lack of B6 in food alone.

Comparison of B6 Deficiency Causes


Cause	Mechanism	At-Risk Population
Inadequate Dietary Intake	Insufficient consumption of B6-rich foods.	Individuals with malnutrition, alcoholism, or restrictive diets.
Malabsorption Disorders	The small intestine cannot properly absorb nutrients.	Those with celiac disease, Crohn's disease, or who have had bariatric surgery.
Medication Interactions	Some drugs interfere with the body's B6 metabolism.	Patients taking isoniazid for tuberculosis or certain antiseizure medications.
Kidney Disease	Impaired kidney function can lead to increased metabolic clearance of B6.	People with end-stage renal disease or on dialysis.
Chronic Alcohol Use	Alcohol breaks down into acetaldehyde, which reduces the active form of B6.	Individuals with alcohol dependence.

How is B6 Deficiency Diagnosed?

Diagnosis typically involves a clinical evaluation by a healthcare professional, combined with blood tests to measure the level of pyridoxal 5'-phosphate (PLP), the active form of B6. A review of symptoms, medical history, and dietary habits is also crucial.

Treatment Options

Treatment for a B6 deficiency is generally straightforward and focuses on correcting the underlying cause while increasing B6 intake. For most adults, this involves oral supplementation, with higher doses sometimes required for severe deficiencies or specific medical conditions. Dietary changes, including incorporating more B6-rich foods, are also a vital part of the recovery process. Rich sources include fish, poultry, potatoes, and fortified cereals. In severe cases or when oral supplements are not effective, a physician may administer B6 intravenously.

Conclusion

Low levels of vitamin B6 can trigger a wide range of health problems affecting the nervous system, skin, and immune function. Recognizing the symptoms and identifying the root cause is crucial for effective treatment. While overt deficiency is rare in many developed countries, certain medical conditions, medications, and lifestyle factors can put individuals at a higher risk. By working with a healthcare provider to ensure adequate B6 levels, individuals can mitigate symptoms and prevent long-term complications. Proper diagnosis and treatment are key to restoring health and well-being. For more detailed clinical information on vitamin B6, a useful resource is the NIH Office of Dietary Supplements(https://ods.od.nih.gov/factsheets/VitaminB6-Consumer/).

Frequently Asked Questions

Early signs of low B6 can be subtle and non-specific. They may include fatigue, irritability, and skin issues like a scaly rash. As the deficiency worsens, symptoms become more pronounced.

Yes, a deficiency in vitamin B6 can affect mental health. It plays a key role in the synthesis of neurotransmitters that regulate mood, and low levels have been linked to depression and confusion.

Several medical conditions can cause low B6, including chronic alcohol use, kidney disease, malabsorption disorders like celiac disease and Crohn's disease, and autoimmune disorders such as rheumatoid arthritis.

To increase B6 levels, include foods such as poultry, fish (like tuna and salmon), beef liver, chickpeas, potatoes, and fortified cereals in your diet.

Most people get enough B6 from a balanced diet, so supplements are not necessary for everyone. They are generally recommended for individuals with a diagnosed deficiency or those at a higher risk due to diet or medical conditions.

A B6 deficiency is primarily diagnosed through clinical evaluation, including a review of symptoms and medical history. Blood tests measuring plasma pyridoxal 5'-phosphate (PLP) levels are also used to confirm the diagnosis.

Yes, some medications can interfere with B6 metabolism and lead to a deficiency. This includes isoniazid (used for tuberculosis), certain antiseizure drugs, and penicillamine.