Medication-Food Interactions: Key Pairs to Avoid

Clinically significant food-drug interactions alter pharmacokinetics or pharmacodynamics:

Food/Component	Medication Class	Interaction Mechanism	Clinical Effect
Grapefruit juice (furanocoumarins)	CYP3A4 substrates: statins (simva, lovasta, atorva), CCBs (felodipine, nifedipine), some benzos, immunosuppressants	Irreversible CYP3A4 inhibition (gut)	↑ Drug levels → toxicity (rhabdo, hypotension, sedation)
Dairy (Ca²⁺, Mg²⁺)	Tetracyclines, fluoroquinolones	Chelation → ↓ absorption	Treatment failure
Tyramine-rich (aged cheese, cured meat, fermented soy, red wine)	MAOIs (phenelzine, tranylcypromine)	Displaced NE → hypertensive crisis	Stroke, intracranial hemorrhage
High potassium (banana, potato, spinach)	K⁺-sparing diuretics (spironolactone, triamterene), ACEi/ARB + K⁺ supplement	Additive K⁺ retention	Hyperkalemia → arrhythmia
Vitamin K (kale, spinach, broccoli)	Warfarin	Antagonizes VKA	↓ INR → thrombosis risk
Alcohol	Disulfiram, metronidazole, CNS depressants	Disulfiram: ALDH inhibition; others: additive sedation	Flushing, nausea, hypotension, respiratory depression
Caffeine	Stimulants (methylphenidate), theophylline, clozapine	Additive CNS stimulation / CYP1A2 inhibition	Anxiety, insomnia, tachycardia, toxicity

General Principles

• Consistent diet (especially vitamin K for warfarin).
• Separate dosing: 2–4 hr for chelation interactions.
• Pharmacist review at each prescription change.
• Patient education: written list, not just verbal.

Individual variability (genetics, microbiome, disease) modifies risk.