NutriStack
Activated Charcoal and Phenytoin, timing-sensitive.
Activated charcoal can strongly adsorb phenytoin in the gut and reduce its absorption. In volunteer data, charcoal given immediately after phenytoin almost completely prevented absorption, and multiple-dose charcoal is used clinically to enhance elimination in phenytoin toxicity. Unsupervised charcoal use can therefore lower phenytoin levels and increase seizure risk.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
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At a glance
- Substances
- Activated Charcoal and Phenytoin
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Strong
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Timing Sensitive · Strong evidence
Timing Sensitive
What is happening. Activated charcoal can strongly adsorb phenytoin in the gut and reduce its absorption. In volunteer data, charcoal given immediately after phenytoin almost completely prevented absorption, and multiple-dose charcoal is used clinically to enhance elimination in phenytoin toxicity. Unsupervised charcoal use can therefore lower phenytoin levels and increase seizure risk.
Mechanism. Activated charcoal has a large adsorptive surface and binds many organic drugs within the gastrointestinal lumen. It can prevent phenytoin absorption after oral dosing and, with repeated doses, may increase elimination by interrupting gastrointestinal recirculation.
Recommendation. Do not take activated charcoal as a wellness supplement while using phenytoin unless your clinician specifically directs it for poisoning management. If charcoal is unavoidable, separate it from phenytoin by at least 4-6 hours and ask whether a phenytoin level should be checked. Seek care promptly for breakthrough seizures, severe dizziness, or loss of coordination.
Minimum separation. 360
Sources (3)
- Neuvonen PJ, Elfving SM, Elonen E. Reduction of absorption of digoxin, phenytoin and aspirin by activated charcoal in man. Eur J Clin Pharmacol. 1978;13(3):213-218. PMID 668776
- American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. Position statement and practice guidelines on the use of multi-dose activated charcoal in the treatment of acute poisoning. J Toxicol Clin Toxicol. 1999;37(6):731-751. PMID 10584586
- Skinner CG, Chang AS, Matthews AS, Reedy SJ, Morgan BW. Randomized controlled study on the use of multiple-dose activated charcoal in patients with supratherapeutic phenytoin levels. Clin Toxicol (Phila). 2012;50(8):764-769. PMID 22897408
Stack Score
How this pair moves the number.
Effect on the composite score
If both Activated Charcoal and Phenytoin are in the same stack, this pair applies −5 to your Stack Score (per scored timing-sensitive row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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