Appendix 6d:
Drug – Food Interactions

Several drugs when given orally can interact with food consumed by the patients. Table 1 shows the medications which should be taken on an empty stomach.

Table 1: Medications which should be taken on an EMPTY STOMACH

Drug Food interactions and effect
Ampicillin Reduced absorption
Alendronate Decreased bioavailability
Azithromycin Reduced absorption
Bisacodyl Dissolves enteric coating
Didanosine Decreased absorption
Indinavir Reduced absorption with fat, proteins
Isoniazid Reduced absorption
Isosorbide dinitrate Delayed absorption
Levothyroxine Reduced absorption; anionic exchange resins reduce absorption
Melphalan Reduced absorption
Methotrexate Reduced absorption
Mycophenolate Enhanced absorption
Omeprazole Delayed absorption
Oxytetracycline Reduced absorption when taken with dairy products.
Rifampin Delayed absorption
Roxithromycin Reduced absorption
Sulfadiazine Formation of crystalluria on consumption with vitamin C or acidifying agents
Tacrolimus Reduced absorption
Tetracycline Reduced absorption, especially when taken with antacids or dairy products
Thyroid Reduced absorption
Typhoid vaccine (oral) Reduced absorption
Zidovudine Enhanced absorption

Food can also impact the effectiveness of a drug due to the way it is consumed. Generally, medicine is to be taken almost at the same time the food is eaten. This is because the medicine may upset the stomach, if the stomach is empty. Certain medications are recommended to be taken with food (Table 2).

Table 2: Medications which should be taken WITH FOOD

Drug Food interactions and effect
Acetylsalicylic Acid Reduced side effects.
Allopurinol Reduced side effects; reduced clearance of active metabolite with protein-poor diet
Amiodarone Enhances both the rate and extent of absorption
Amoxycillin/clavulanic acid Reduced side effects
Azathioprine Reduced side effects
Baclofen Reduced side effects
Bromocriptine Reduced side effects
Carbamazepine Increased absorption
Cefuroxime Increased absorption
Chloroquine Reduced side effects
Clofazimine Increased drug absorption
Conjugated estrogens Reduced side effects
Diclofenac Reduced peak concentration but not extent of absorption; reduced side effects
Doxycycline Reduced side effects; reduced absorption with milk
Ethinyl estradiol Reduced side effects
Ferrous salts Take between meals, if gastrointestinal upset occurs take with food
Griseofulvin Increased rate or extent of absorption with fats; reduced side effects
Hydroxychloroquine Reduced bowel side effects; masks the bitter taste of drug
Hydrocortisone Slows rate of absorption; reduced peak levels; reduced side effects
Ibuprofen Reduced side effects
Iron preparations See iron salts
Levocetirizine May be taken with or without food
Lithium Reduced side effects
Mebendazole Increased absorption
Methadone Reduced side effects
Methylprednisolone Reduced side effects
Metronidazole Reduced side effects
Mexiletine Reduced side effects; slows rate of absorption; reduces rate of caffeine clearance
Morphine Increased absorption
Nelfinavir Greatly increases absorption and AUC
Niacin Reduced absorption; decreases side effects
Nitrofurantoin Increased absorption
Pioglitazone Food slightly delays absorption rate but extent of absorption is not affected
Potassium salts Reduced side effects
Prednisolone Reduced side effects
Prednisone Reduced stomach irritation
Procainamide Reduced side effects; increased absorption with fat
Propranolol Slows rate but increases extent of absorption
Quinine Reduced side effects
Ritonavir Increased absorption
Salsalate Reduced stomach irritation
Saquinavir Increased absorption
Sodium chloride Reduced side effects
Spironolactone Increased absorption; reduced side effects
Sulfasalazine Reduced side effects
Sodium valproate Reduced side effects

Table 3: Selected herbal or food products resulting in adverse effects

Herb/Food Drug Adverse Effects/Reported Drug Interactions/ Remark
Licorice Digoxin Spironolactone Elevates serum digoxin levels 4-fold, arrhythmias Hypokalemia and muscle weakness
Foods high in vitamin K (broccoli, sprouts, turnip greens, spinach, cauliflower, legumes, mayonnaise, soybean oils and fish Anticoagulants (warfarin) Such foods may reduce the effectiveness of anticoagulants, increasing the risk of clotting. Intake of such foods should be limited, and the amount consumed daily should remain constant
Foods high in sodium (like licorice, processed meats, canned foods) Amlodipine Such foods decrease the effectiveness of the drug
Calcium or foods containing calcium (milk and other dairy products) Tetracycline These foods can reduce the absorption of tetracycline, which should be taken 1 h before or 2 h after eating
Foods high in tyramine, (includes cheese, yoghurt, sour cream, cured meats, liver, dried fish, bananas, yeast extracts, raisins, soya sauce, red wine, certain beers) MAO - inhibitors (such as phenelzine and tranylcypromine) Severe headache and a potentially fatal increase in BP (hypertensive crisis) can occur if people taking MAO - inhibitors consume these foods. These foods must be avoided