Phenytoin

Comprehensive clinical interaction and dietary monograph for Phenytoin (Phenytoin).

Generic Active Chemical: Phenytoin

Brand Formulations:DilantinPhenytek

Quick Jump:Kitchen Foods (1)Drug Red Flags (1)Supplements & Herbs (1)Administration Timing (0)Pairwise Combos (2)

Kitchen Food, Drink & Dietary Conflicts

Biochemical interactions with common foods, beverages & cooking ingredients

1 Flagged Foods

HIGH

Alcoholic Beverages (Beer, Wine, Spirits)

NutriDive Kitchen Food Biochemical Ontology & openFDA

Bioactive Compound:Ethanol

Biological Target:GABA-A Receptors, Hepatic CYP2E1 & Gluconeogenesis

Clinical Mechanism:

Multiplies respiratory depression and profound sedation with opioids and sedatives; blocks hepatic lactate uptake with metformin (lactic acidosis); triggers acute disulfiram-like vomiting and tachycardia with metronidazole; and accelerates dose-dumping in extended-release capsules.

Patient Actionable Rule:Completely abstain from alcohol while taking metronidazole, cephalosporins, prescription sedatives, or empty-stomach metformin.

Prescription & OTC Drug Interactions (DDI)

Documented pharmacological conflicts & contraindicated co-prescriptions

1 Warning Classes

HIGH RISK

NSAIDs (Ibuprofen, Naproxen) & Non-Cardioprotective Analgesics

openFDA SPL Section 7 (Drug Interactions)

Mechanism: Inhibition of renal vasodilatory prostaglandins (PGI2, PGE2) causes afferent arteriolar vasoconstriction, blunts blood pressure control, and increases risk of acute kidney injury (AKI).

Clinical Consequence: Loss of blood pressure reduction, fluid retention, or acute renal hemodynamic compromise.

Physician Precaution: Consult your physician before taking OTC pain relievers. Acetaminophen may be preferred for occasional pain depending on liver status.

Dietary Supplements, Herbs & Minerals (DNI)

Interactions with over-the-counter vitamins, minerals, and herbal preparations

1 Monitored

HIGH

St. John's Wort (Hypericum perforatum)

NIH National Center for Complementary and Integrative Health (NCCIH)

Biological Target: Hepatic Cytochrome P450 3A4 / 2C9 & P-glycoprotein (P-gp)

Hyperforin potently activates the Pregnane X Receptor (PXR), inducing hepatic CYP enzymes and intestinal P-gp pumps. This accelerates medication clearance and precipitates therapeutic failure.

Guidance & Spacing:Completely avoid herbal St. John's Wort while taking prescription medications.

Chronotherapy & Meal Administration Protocols

Optimal absorption, meal-timing rules & GI tolerability protocols

0 Protocols

Frequently Researched Drug-Substance Combinations

Explore pairwise interaction dossiers and laboratory safety analyses

HIGH→

Phenytoin and Aspirin / NSAIDs

Pairwise Clinical Analysis & Safety Rating

HIGH→

Phenytoin and Alcoholic Beverages

Pairwise Clinical Analysis & Safety Rating

Multi-Substance Interactive Radar

Taking Phenytoin alongside daily coffee, supplements, or other medications?

Add all your daily medications, foods (Dairy, Spinach, Coffee, Grapefruit), and botanicals (Ashwagandha, Curcumin, Melatonin) into the SafeStack interactive engine to run full multi-way synergy collision analysis in real time.

Launch SafeStack Radar with Phenytoin→

Authoritative Clinical Evidence & Regulatory Sources

Data on this clinical monograph is compiled from the U.S. National Library of Medicine (MedlinePlus), openFDA Structured Product Labeling (SPL Section 7 Drug Interactions), the NIH Office of Dietary Supplements (ODS), and Krause and Mahan's Food & Nutrition Care Process.

View Original NLM MedlinePlus Monograph·Clinical & Legal Disclaimers