What Happens to Excess B6 in the Body?

January 4, 2026 •

2 min read

Although vitamin B6 is a water-soluble vitamin, which are generally excreted by the body, an excess of B6 can be harmful, with all reported cases of toxicity linked to high-dose supplementation. The body's normal excretion process can be overwhelmed, leading to a buildup that primarily affects the nervous system.

Quick Summary

The body can typically excrete surplus B6 from food, but high doses from supplements can lead to a toxic buildup, primarily damaging the peripheral nerves. This condition, called peripheral neuropathy, causes symptoms like numbness, tingling, and poor coordination. Stopping supplementation is the main treatment, although nerve damage may sometimes be permanent. Monitoring intake from all sources is crucial to prevent toxicity.

Key Points

Excretion: Excess B6 from dietary sources is normally metabolized and excreted in the urine.
Toxicity Source: All reported cases of B6 toxicity are linked to high-dose supplementation.
Nerve Damage: Excessive B6 intake can lead to peripheral neuropathy, causing numbness, tingling, and poor coordination.
Recovery: Symptoms often improve after stopping supplementation, but nerve damage may be permanent.
Safe Limits: The Tolerable Upper Intake Level (UL) for adults is 100 mg per day, though adverse effects have been reported at lower doses.
Hidden Sources: B6 is often an ingredient in B-complex, multivitamins, and magnesium supplements.
Mechanism: The inactive form of B6 in supplements can interfere with the body's active form.

The Body's Excretion of Water-Soluble Vitamins

Vitamin B6, also known as pyridoxine, is a water-soluble vitamin. The body does not store significant amounts. Excess B6 from food is usually metabolized and excreted in urine, making toxicity from food rare.

Why Supplementation Poses a Risk

Harm occurs with long-term, high-dose B6 supplements, which often exceed the adult recommended daily allowance (RDA) of 1.3-1.7 mg. The body's ability to excrete excess B6 becomes overwhelmed, leading to accumulation and toxicity.

The Impact of Excess B6 on the Nervous System

The most serious effect of high B6 is peripheral neuropathy, damage to nerves outside the brain and spinal cord, particularly in the hands and feet. Symptoms include numbness, tingling, loss of coordination (ataxia), reduced sensation, and muscle weakness. While symptoms often improve upon stopping supplements, damage can be permanent.

Other Symptoms of B6 Hypervitaminosis

Beyond nerve issues, high B6 can cause skin lesions, photosensitivity, gastrointestinal issues like nausea and heartburn, and dizziness.

Important Considerations for Preventing Toxicity

B6 is often included in other supplements, potentially leading to high intake. Check labels and total daily intake from all supplements. The tolerable upper intake level (UL) for adults is typically set at 100 mg per day, although adverse effects can occur at lower doses.

Comparison of Water-Soluble Vitamin Excess

Here's how B6 compares to other water-soluble vitamins regarding excess intake:


Vitamin	Storage in Body	Excess Excretion	Risk of Toxicity from Supplements	Primary Excess Concern
B6 (Pyridoxine)	Limited, but excess can accumulate	Excreted in urine	High risk with long-term, high-dose supplementation	Peripheral neuropathy
B12 (Cobalamin)	Stored for years	Excreted via urine, slow clearance	Very low risk	None typically
Vitamin C (Ascorbic Acid)	Limited	Excreted rapidly in urine	Low risk, can cause digestive upset	Digestive distress
B1 (Thiamine)	Limited	Excreted rapidly in urine	Extremely low risk	None known

Conclusion

While the body efficiently handles B6 from food, high supplement doses can overwhelm this system. This can lead to peripheral neuropathy, a serious condition causing symptoms like numbness and lack of coordination. Symptoms can resolve after stopping supplements, but permanent damage is possible. Be mindful of supplement intake and consult a healthcare professional.

For additional information and guidance on vitamin B6 toxicity, consult the fact sheets from the National Institutes of Health (NIH) Office of Dietary Supplements.

Frequently Asked Questions

No, it is extremely rare to get too much B6 from dietary sources alone. The body is highly efficient at processing and excreting any surplus B6 from the food you eat.

The most common early signs of B6 toxicity are tingling, numbness, or a burning sensation in the hands and feet. This is often described as a 'stocking-glove' sensation.

B6 toxicity typically occurs after a long period of taking high-dose supplements, often for a year or longer. However, sensitivity varies, and some people may experience issues at lower doses or shorter durations.

In most cases, symptoms of B6 toxicity gradually improve and can resolve completely after stopping supplementation. However, if the nerve damage is severe or has persisted for a long time, some damage may be permanent.

For most adults, the Tolerable Upper Intake Level (UL) is 100 mg per day from all sources. The recommended daily allowance is much lower, typically around 1.3-1.7 mg.

B6 is a vital nutrient for numerous bodily functions, and it's a common ingredient in B-complex vitamins, multivitamins, and other supplements like magnesium. Manufacturers often include it without highlighting the potential for toxicity at high doses.

Diagnosis involves a thorough review of the patient's medical history, including supplement use. A physical exam, especially a neurological assessment, is performed, and blood tests may be ordered to measure B6 levels.