NutriStack
Phenytoin and Vitamin B6, a synergy.
Enzyme-inducing antiseizure drugs such as phenytoin have been associated with vitamin B6 deficiency. Low B6 can contribute to neuropathy symptoms and impaired homocysteine metabolism, especially when folate or B12 status is also poor. This is a monitoring and repletion issue, not a reason to stop phenytoin abruptly.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Phenytoin and Vitamin B6
- Pair type
- Synergy
- Evidence (highest tier)
- Moderate
- Source citations
- 2 sources
- Stack Score effect
- +2 to your Stack Score (per scored synergy row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Synergy · Moderate evidence
Synergy
What is happening. Enzyme-inducing antiseizure drugs such as phenytoin have been associated with vitamin B6 deficiency. Low B6 can contribute to neuropathy symptoms and impaired homocysteine metabolism, especially when folate or B12 status is also poor. This is a monitoring and repletion issue, not a reason to stop phenytoin abruptly.
Mechanism. Phenytoin is an enzyme-inducing antiseizure medication and may lower pyridoxine status through increased vitamin turnover or altered metabolism. Vitamin B6 is required for transsulfuration of homocysteine and for normal peripheral nerve function.
Recommendation. Ask about B-vitamin or homocysteine testing if you take phenytoin long term, especially if you have neuropathy symptoms or cardiovascular risk factors. Use conservative B6 doses unless deficiency is documented and supervised. Do not take chronic high-dose B6 without monitoring because excess B6 can damage nerves.
Sources (2)
- Mintzer S, Skidmore CT, Sperling MR. B-vitamin deficiency in patients treated with antiepileptic drugs. Epilepsy Behav. 2012;24(3):341-344. PMID 22658435
- Tamura T, Aiso K, Johnston KE, Black L, Faught E. Homocysteine, folate, vitamin B-12 and vitamin B-6 in patients receiving antiepileptic drug monotherapy. Epilepsy Res. 2000;40(1):7-15. PMID 10771253
Stack Score
How this pair moves the number.
Effect on the composite score
If both Phenytoin and Vitamin B6 are in the same stack, this pair applies +2 to your Stack Score (per scored synergy row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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