Supplement stacks / Phenytoin + Vitamin B12
Can You Take Phenytoin with Vitamin B12?
Phenytoin and Vitamin B12: one interaction flagged, scored 7/10 (medium risk). The count and score come from an AI-written analysis checked against our interaction rules, which can only make it stricter. Not medical advice.
Safety at a glance
This score comes from an AI-written analysis of the pair. Our interaction rules check it and can only make it stricter, never milder. Informational only: it can't account for your medications, conditions, or genetics.
What the AI-written analysis says
Phenytoin is an anticonvulsant medication that can interact with various supplements, including Vitamin B12. While Vitamin B12 is generally safe, there is a potential for phenytoin to affect its absorption and metabolism. Caution is advised when taking these together, and monitoring is recommended.
Phenytoin is a prescription medication. This page describes publicly documented interactions — it can't see your dose, your other prescriptions, or your labs. Discuss any supplement with the prescriber or pharmacist who manages this medication before combining.
Known interactions
Phenytoin may reduce the absorption of Vitamin B12, potentially leading to deficiency. It is advisable to separate the intake of these substances by at least 4 hours.
Phenytoin
From the AI-written analysis.
Phenytoin has a narrow therapeutic index and can cause side effects such as dizziness, drowsiness, and potential interactions with other medications and supplements.
Typical dosage: As prescribed or as directed on the label
- Dizziness
- Drowsiness
- Nausea
- Gingival hyperplasia
- Monitor for signs of toxicity; regular blood level checks may be necessary.
- Consult healthcare provider before adding any new supplements.
Vitamin B12
From the AI-written analysis.
Generally considered safe with low risk of toxicity; however, high doses may lead to rare side effects.
Typical dosage: Typically 2.4 mcg per day for adults; follow manufacturer guidelines.
- Mild diarrhea
- Itching
- Rash
- Consult healthcare provider if you have a history of anemia or other health conditions.
- Monitor for signs of deficiency if taking with phenytoin.
Timing
Take as prescribed — we do not schedule prescription medications. Follow the label or your prescriber, and ask your pharmacist before changing when you take it.
Frequently asked questions
Can you take Phenytoin and Vitamin B12 together?
Phenytoin and Vitamin B12: one interaction flagged, scored 7/10 (medium risk). The count and score come from an AI-written analysis checked against our interaction rules, which can only make it stricter. Not medical advice.
What score does the Phenytoin and Vitamin B12 combination get?
The Phenytoin and Vitamin B12 combination is scored 7/10 (medium risk). The score comes from an AI-written analysis checked against our interaction rules, which can only make it stricter. Not medical advice. Always confirm with a healthcare professional.
When should you take Phenytoin and Vitamin B12?
Take as prescribed — we do not schedule prescription medications. Follow the label or your prescriber, and ask your pharmacist before changing when you take it.
Check your full stack
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Not medical advice
AI-written analysis generated August 28, 2026, checked by our interaction rules · How our analysis works