Scheduling Changes for Vitamin B6

The Therapeutic Goods Administration (TGA) has finalised its decision regarding the scheduling of vitamin B6. Vitamin B6 is a general term used to describe the compounds, pyridoxine, pyridoxal, and pyridoxamine, and their respective phosphate esters.

Table 1 shows the updates that will occur to the Poisons Standard for oral products containing vitamin B6. Products are classified according to the recommended daily dose (RDD).

Table 1. Scheduling changes for oral preparations of vitamin B6 for human therapeutic use

A new Schedule 3 entry will be created for products containing 50-200mg of vitamin B6 per RDD. These products will no longer be available in supermarkets and health food stores and will require pharmacist consultation prior to purchase.

The implementation date for these changes has been set at 1 June 2027.

Reasons for Decision

Vitamin B6 is a water-soluble vitamin involved in over 100 enzymatic reactions, primarily those involved in protein metabolism. This vitamin is naturally present in a range of foods, is added to some foodstuffs, and is available in many supplements.

While vitamin B6 is water-soluble, it can accumulate in the body. Pyridoxine has a relatively long elimination half-life of around 15 to 30 days. This means that even small daily doses can accumulate over time, potentially leading to toxicity.

Signs and symptoms of vitamin B6 toxicity include paraesthesia, hyperaesthesia, weakness, atrophy, reduced reflexes, fasciculation, numbness, and pain. While both small and large-fibre neuropathies can occur, small-fibre dysfunction is thought to be the most common presentation. These are often more difficult to diagnose and may lead to underreporting.

As of October 2025, the TGA had received 250 reports of peripheral neuropathy, peripheral sensorimotor neuropathy, small fibre neuropathy, polyneuropathy or chronic polyneuropathy for products containing vitamin B6. An additional 162 reports of ‘Hypervitaminosis B6’ or ‘Vitamin B6 increased’ were received with less specific reaction terms that may be indicative of neuropathies (e.g. paraesthesia, burning sensation, etc.).

While it has been traditionally thought that nerve damage is only seen with chronic ingestion of high doses of vitamin B6, evidence suggests that toxicity is possible even at relatively low doses. Research findings also indicate significant inter-individual variation may exist in the metabolism of vitamin B6.

Where symptoms of excessive vitamin B6 occur, improvements are often achieved when supplementation is ceased or reduced. However, long-lasting or permanent nerve damage has been reported.

The TGA requires all vitamin B6-containing listed medications with a recommended daily dose exceeding 10 mg to include a paraesthesia warning.

Recommended intake for vitamin B6

The Australian recommended dietary intake (RDI) for vitamin B6 ranges from 0.1 mg/day for infants 0–6 months to 1.7 mg/day for men over 50 years, and as high as 1.9 mg/day during pregnancy and 2.0 mg/day during breastfeeding.

As vitamin B6 is found in a wide range of foods and has high bioavailability, deficiency is considered rare in Australia. Signs and symptoms of deficiency include seborrhoeic dermatitis, convulsions, microcytic anaemia, depression, and confusion. Populations that may be more likely to experience deficiency include the elderly, and those with alcohol dependence, malabsorption syndromes, or certain kidney, liver and autoimmune conditions. Some medications, such as isoniazid, penicillamine, and hydralazine, may also increase vitamin B6 requirements.

The upper level of intake (UL) can be defined as the highest average daily nutrient intake level likely to pose no adverse health effects for almost all individuals in the general population. Increasing intake above the UL increases the potential risk of adverse effects. In Australia, the UL for vitamin B6 (as pyridoxine) ranges from 15mg/day for young children up to 50mg/day in adults. However, it is worth noting that the European Food Safety Authority (EFSA) recently reduced its adult UL to 12.5mg/day. This decision was made following a review that found evidence that nerve damage may occur at lower doses than previously thought.

The Australian National Health and Medical Research Council (NHMRC) is reviewing the UL of vitamin B6. The TGA advises that the limits set in their final decision will be re-evaluated if the NHMRC implement any changes.

Products containing vitamin B6

Complementary products containing vitamin B6 include products with a range of marketed indications, including:

• Vitamin B6 or B-complex supplements;
• Multivitamin and mineral formulas;
• Mental function;
• Women’s health;
• Hair, skin and nails support;
• Weight-loss and sports performance;
• Muscle cramps;
• Migraine; and
• Gout.

Many products currently available over-the-counter exceed the UL for vitamin B6 when taken on their own as directed. It also may not be obvious from the front label that these products contain a significant amount of vitamin B6. The risk here is that people may unknowingly take multiple products containing vitamin B6, putting themselves at risk of high cumulative exposure and potential nerve damage.

The new scheduling for higher dose products (50mg to ≤ 200mg RDD) means that these medicines will no longer be available for self-selection. It is anticipated that the creation of this Schedule 3 listing will reduce the risk of individuals inadvertently taking high doses of vitamin B6. Consumers will receive advice from a healthcare professional rather than having to rely on reading and interpreting the fine print on labels themselves.

Uses for High Dose Vitamin B6

There is evidence to support the use of high doses of vitamin B6 for a limited number of indications, although these patients would be managed by a medical professional.

Isoniazid poisoning

Isoniazid induces a state of functional pyridoxine deficiency by at least two mechanisms:

1. Metabolites of isoniazid directly attach to and inactivate pyridoxine species.
2. Inhibition of pyridoxine phosphokinase, the enzyme responsible for activating pyridoxine to pyridoxal 5′ phosphate.

Pyridoxine supplementation (e.g. 25mg with each isoniazid dose) is regularly used with isoniazid therapy to reduce the risk of peripheral neuropathy. Higher pyridoxine doses are used in cases of isoniazid poisoning.

In acute isoniazid poisoning complicated by seizures or metabolic acidosis, up to 5g of pyridoxine may be given as a single dose. A repeat dose may be warranted if signs and symptoms do not resolve after 30 minutes. Intravenous administration is preferred in these cases. However, a parenteral formulation is not currently registered in Australia. If intravenous pyridoxine is not available or the supply is inadequate, the Therapeutic Guidelines advise that oral pyridoxine can be used. Care is required if administered orally with activated charcoal as this significantly reduces pyridoxine bioavailability.

Pyridoxine-dependent epilepsy

This is a rare condition that usually presents with seizures during infancy. These seizures can be controlled with large doses of pyridoxine, and this must be continued for life. The Therapeutic Guidelines recommend daily doses of 50 to 100mg. Doses may be doubled during acute febrile illness to prevent exacerbation of seizures.

Nausea and vomiting during pregnancy

The Therapeutic Guidelines provides advice on the use of pyridoxine to manage nausea and vomiting during pregnancy. For this purpose, pyridoxine may be administered as a 12.5mg dose in the morning and at midday, followed by a 25mg dose at night.

Summary

Vitamin B6 toxicity can cause neurological injury, particularly when intake occurs over long periods or where the daily dose exceeds 200 mg. However, peripheral neuropathy has been reported with daily doses under 50 mg.

Many supplements and complementary medicines contain sufficient vitamin B6 to cause toxicity when taken as directed. Many of these products are not marketed as a vitamin B6 supplement. Therefore, there is the real risk that consumers may unintentionally take more than one product with significant amounts of vitamin B6. This highlights the importance of specifically asking patients about their use of complementary medicines when taking a medication history.

The upcoming scheduling changes are intended to make it easier for consumers to recognise when a product contains vitamin B6. It will also reduce the risk of people accessing high amounts of vitamin B6 without consultation with a healthcare professional.