Other drug interactions | Drug interactions and contraindications | Medications

Drug-food/beverage/nutrient interactions

Drugs can interact with food in various ways. Some medications, e.g., levothyroxine, should be taken on an empty stomach as food reduces the absorption of certain drugs. Alcohol can potentiate the effects of drugs like Valium (diazepam), besides causing adverse effects.

Common drug-food interactions

Drug-food combination	Effect
MAO inhibitors + high tyramine foods (cheese, wine, cured meats, bananas, etc.)	Potentially fatal increase in blood pressure, headache
Warfarin + Vit K-rich foods (kale, broccoli, etc.)	Reduced effect of warfarin causing blood clots
Digoxin + oatmeal	Decreased absorption due to high fiber
Bisphosphonates + any food	Decreased absorption and effect
Tetracycline + milk/dairy products	Decreased absorption from forming calcium complexes

Drug-condition/disease interactions

Occur when a disease condition puts an individual at higher risk of adverse effects from taking certain medications. For example, hypertension and nasal decongestants could cause dangerously elevated blood pressure; beta blockers like propranolol in a patient with asthma can precipitate severe asthma; and high-dose acetaminophen in a patient with liver disease can cause toxicity.

Drug-laboratory interactions

Certain drugs can interfere with and change laboratory test results by altering the specimen or reacting with the test reagents. Examples are Biotin supplements erroneously lowering troponin levels in laboratory tests, thus interfering with the diagnosis of heart attacks; cephalosporin antibiotics causing false positive glucose and ketone tests; and PPIs like omeprazole, which interfere with the INR test (for evaluating blood clotting).

Drug interactions with herbal supplements

Herbal supplement	Drug involved	Effect
CoQ-10	Warfarin Blood pressure medications	Risk of clotting Decreased blood pressure
Danshen	Warfarin, clopidogrel, aspirin Digoxin	Risk of bleeding Digoxin toxicity
Evening primrose; Saw palmetto	Warfarin, clopidogrel, aspirin	Risk of bleeding
Ginkgo biloba	Warfarin, clopidogrel, aspirin	Risk of bleeding
Hawthorn	Digoxin and other cardiac medications	Risk of toxicity like bradycardia, hypotension, arrhythmias, cardiac arrest
Licorice	Warfarin Digoxin	Risk of clotting Digoxin toxicity
St.John’s wort	Warfarin Multiple interactions with cardiac drugs, statins, immunosuppressants, antidepressants, benzodiazepines, anti-epileptics, birth control pills, anti-HIV drugs	Risk of clotting Decreased effect, increased toxicity