Drug-Food Interactions

Warfarin + Vitamin K

↓ Warfarin effectiveness; vitamin K can counteract its anticoagulant effect.

Warfarin + NSAIDs

↑ Risk of GI bleeding and increased anticoagulant effects.

Insulin/oral diabetes drugs + alcohol

↑ Risk of hypoglycemia (low blood sugar).

Digoxin + high-fiber foods

↓ Digoxin absorption → ↓ effectiveness.

Digoxin + ginseng

↑ Digoxin blood levels.

Digoxin + St. John's Wort

↓ Digoxin blood levels.

Statins + grapefruit

↑ Blood levels of some statins → ↑ side effects.

Calcium channel blockers + grapefruit

↑ Drug blood levels → ↑ risk of side effects.

Sildenafil + grapefruit

May ↑ sildenafil blood levels → hypotension and other side effects.

Acetaminophen + alcohol

↑ Risk of liver toxicity.

Tetracyclines + dairy

Calcium can bind the antibiotic → ↓ absorption.

Ciprofloxacin + dairy

Calcium can bind the antibiotic → ↓ absorption.

MAOIs + tyramine

Can cause a hypertensive crisis (dangerously high blood pressure).

Antithyroid drugs + iodine-rich foods

High iodine intake can reduce effectiveness of antithyroid drugs.

Fluoxetine + MAOI

Can cause serotonin syndrome.

Digoxin + quinidine

↑ Digoxin blood levels → risk of serious toxicity.

Sildenafil + nitrates

Can cause severe hypotension (dangerously low blood pressure).

Potassium + spironolactone

↑ Risk of hyperkalemia (high potassium).

Clonidine withdrawal + propranolol

Can cause rebound hypertension.

Theophylline + ciprofloxacin

↑ Theophylline levels → risk of toxicity.

Pimozide + ketoconazole

↑ Pimozide levels → QT prolongation and potentially dangerous arrhythmias.

Methotrexate + probenecid

↑ Methotrexate levels → risk of toxicity.

Bromocriptine + pseudoephedrine

Can cause severe vasoconstriction and cardiovascular effects.

Tyramine-containing foods

Examples: some red wines, malt beer, smoked fish, aged cheeses, and dried fruits.

Vitamin K-rich foods

Examples: kale, collards, spinach, turnip greens, Brussels sprouts, broccoli, scallions, asparagus, and endive.

Iodine-rich foods

Examples: seafood, seaweed, kelp, nori, and iodized salt.

Grapefruit interaction mechanism

Grapefruit can inhibit CYP3A4, increasing blood levels of certain drugs.

Digoxin toxicity signs

Yellow vision/halos, weakness, confusion, dizziness, nausea, and vomiting.

Serotonin syndrome signs

Mental status changes, agitation, sweating (diaphoresis), and fast heart rate (tachycardia).

Fluoxetine → MAOI washout

Wait at least 5 weeks after stopping fluoxetine before starting an MAOI.

MAOI → SSRI washout

Wait 2 weeks after stopping an MAOI before starting an SSRI.

Digoxin + fiber timing

Take digoxin at least 1 hour before or 2 hours after eating to reduce the absorption interaction.

Key grapefruit memory

GRAPEFRUIT → ↑ drug levels of certain medications.

Key alcohol memory

Alcohol + diabetes medications → LOW blood sugar; Alcohol + acetaminophen → LIVER toxicity.

Key dairy memory

DAIRY + certain antibiotics → ↓ absorption.

Key MAOI memory

MAOI + TYRAMINE → HYPERTENSIVE CRISIS.

Key sildenafil memory

SILDENAFIL + NITRATES → SEVERE HYPOTENSION.

Key potassium memory

POTASSIUM + SPIRONOLACTONE → HYPERKALEMIA.