Vitamin B6 Deficiency: Skin, Mood, and Nerve Signs of Low Pyridoxine

Vitamin B6, also called pyridoxine, is a water-soluble vitamin that serves as a coenzyme in more than 100 enzyme reactions, most of them tied to protein and amino acid metabolism. When intake falls short, the body can signal the gap through changes in skin, mood, and nerve function. If you think you may be deficient, speak with a clinician before starting any supplement.

What Vitamin B6 Actually Does

According to the NIH Office of Dietary Supplements (ODS), vitamin B6 supports amino acid metabolism through its active forms, pyridoxal 5-phosphate (PLP) and pyridoxamine 5-phosphate (PMP). PLP also participates in the metabolism of one-carbon units, carbohydrates, and lipids. One of its best-documented roles is contributing to cognitive development through the biosynthesis of neurotransmitters, including serotonin, dopamine, and gamma-aminobutyric acid (GABA). Vitamin B6 also helps maintain normal blood homocysteine levels, which is considered strong evidence by the NIH ODS.

How Much Do Adults Need?

The NIH ODS reports the following reference values for adults aged 19 to 50 years, regardless of sex:

• Recommended Dietary Allowance (RDA): 1.3 mg per day
• Tolerable Upper Intake Level (UL): 100 mg per day, applying to food and supplement intakes combined

It is worth noting that in 2023 the European Food Safety Authority (EFSA) set a considerably lower upper limit of 12 mg per day for all adults, including during pregnancy and lactation. This difference reflects ongoing scientific discussion about the threshold at which high-dose supplementation may cause harm. Always ask a clinician or pharmacist what level is appropriate for your individual situation.

Signs That May Point to Low Vitamin B6

True deficiency is uncommon in people who eat a varied diet, but certain groups face higher risk, including people with kidney disease, malabsorption conditions, alcohol use disorder, or those taking specific medications. The following signs are associated with low B6 status in clinical and research settings. None of them is specific to B6 alone, so a blood test ordered by a clinician is the appropriate way to confirm a deficiency.

Skin Changes

Low pyridoxine has been linked to a seborrheic dermatitis-like rash, particularly around the nose, mouth, and eyes. Cracked lips and a sore, inflamed tongue (glossitis) are also reported in deficiency states. These skin changes reflect B6's role in protein metabolism and cell turnover. They are not unique to B6 deficiency and can appear with deficiencies of other B vitamins as well.

Mood Disturbances

Because vitamin B6 is involved in the biosynthesis of serotonin, dopamine, and GABA, inadequate levels may affect mood regulation. Irritability, anxiety, and low mood are sometimes reported alongside confirmed deficiency. The NIH ODS notes that evidence for vitamin B6 supplementation improving cognitive function or preventing cognitive decline in older adults is currently insufficient, meaning well-designed studies have not yet produced consistent results.

Separately, preliminary evidence suggests that vitamin B6 at doses of 50 to 100 mg per day in adults may reduce behavioral side effects such as irritability, agitation, and depression associated with the antiepileptic drug levetiracetam (Keppra). This is early-stage evidence and should not be acted on without medical supervision.

Nerve-Related Symptoms

Peripheral neuropathy, which can present as numbness, tingling, or burning sensations in the hands and feet, is one of the more recognized signs of both severe B6 deficiency and, paradoxically, long-term high-dose supplementation. The NIH ODS states clearly that long-term high-dose supplementation can cause sensory neuropathy, which is why the UL exists. If you are experiencing nerve symptoms, consult a clinician rather than self-treating.

In infants, severe deficiency can cause seizures due to disrupted neurotransmitter synthesis, underscoring how central this vitamin is to normal nervous system function.

What the Evidence Says About Supplementation

The NIH ODS grades evidence for vitamin B6 supplementation across several health areas. Here is an honest summary:

• Coenzyme role in protein and amino acid metabolism: Strong evidence
• Maintaining normal blood homocysteine levels: Strong evidence
• Reducing nausea and vomiting in pregnancy: Moderate evidence
• Reducing symptoms of premenstrual syndrome (PMS): Limited evidence
• Reducing risk or severity of cardiovascular disease and stroke: Insufficient evidence
• Preventing cancer or reducing cancer mortality: Insufficient evidence
• Improving cognitive function or preventing cognitive decline in older adults: Insufficient evidence

Supplements are not intended to diagnose, treat, cure, or prevent any disease, and these statements have not been evaluated by the FDA.

Drug Interactions to Know

Vitamin B6 interacts with several medications. Always talk to a doctor or pharmacist before combining B6 supplements with any prescription drug.

• Cycloserine (Seromycin), an antibiotic used for tuberculosis, increases urinary excretion of pyridoxine and can worsen seizures and neurotoxicity. Pyridoxine supplementation may help prevent these effects under medical supervision.
• Antiepileptic drugs including valproic acid (Depakene, Stavzor), carbamazepine (Carbatrol, Epitol, Tegretol), and phenytoin (Dilantin) increase the breakdown of vitamin B6, lowering plasma PLP and raising homocysteine levels.
• Pyridoxine supplementation at 200 mg per day for 12 to 120 days may reduce serum concentrations of phenytoin and phenobarbital, possibly by speeding their metabolism. This could affect seizure control and requires medical oversight.

Food Sources and Practical Takeaways

Most people in the United States meet the 1.3 mg per day RDA through food. Good dietary sources include poultry, fish, organ meats, potatoes, starchy vegetables, and non-citrus fruits. Fortified cereals also contribute meaningfully to intake.

If you suspect a deficiency, the right first step is a conversation with your clinician, not a high-dose supplement. A simple blood test measuring plasma PLP can clarify your status. Personal dosing decisions should be made with a clinician or pharmacist, especially given the gap between the US UL of 100 mg per day and the EFSA's 2023 limit of 12 mg per day.

For full reference data, see the NIH ODS Vitamin B6 fact sheets at ods.od.nih.gov and the National Academies Dietary Reference Intakes report on B vitamins.