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Drug and Food Interactions

Nothing which is natural can cause any health problems. This is a statement which a lot of people consider to be absolutely true. Unfortunately, it is not the case. Anything you put in your mouth can and will interact in some way with everything else which will end up in your body. Those interactions may be especially dangerous with medicines. Food may either enhance or reduce the effect of a medicine and sometimes the result can be deadly. Let’s look at most common drug-food interactions.

*Warfarine (Coumadin).

Warfarine is a potent blood thinning medication which prevents blood clotting. On the other hand, food rich in vitamin K (dark green leafy vegetables, broccoli, Brussel sprouts, cauliflower, legumes) increases clotting and can totally cancel the effects of the medicine. In some preliminary studies, garlic, ginger, turmeric, cranberry juice, fish oil and cooked onions were shown to increase the tendency towards bleeding and thus should be avoided. In case of Warfarine, the main idea is not to make any drastic changes in your diet.

*Statins (Lipitor, Zocor, Mevacor).

Those drugs are used to control high cholesterol. Its proper absorption in the body is regulated by the isoenzyme Cytochrome P450. Grapefruit juice has an ability to suppress this enzyme which causes problems with concentration of the drug in the blood plazma with serious side effects. Grapefruit juice will actually interfere with any drugs which utilizes Cytochrome P450 for proper absorption and elimination such as calcium channel blockers (high blood pressure drugs), Valium, Cyclosporine, Methadone, and Viagra, to name a few. Other foods which interfere with Cytochrome P450 activity are broccoli, cabbage, spinach, onions, garlic, parsley, fried and charcoaled broiled foods, ham, and processed sausages.

*MAO inhibitors.

Those drugs used to treat depression and Parkinson’s disease may interact with tyramine. Reaction between those drugs and tyramine can be very dangerous and lead to a rapid and possible life-threatening increase in blood pressure. Foods and drinks which are high in tyramine: aged cheeses; pickled meats and fish; liver; aged sausages (bologna, salami, pepperoni, summer sausage); sauerkraut; fava beans; beer; red wines.


This drug is used for treatment of congestive heart failure. The effects of digoxin can be substantially lowered by increased intake of insoluble fiber (Bran, oatmeal). Black licorice in combination with digoxin can lead to irregular heart rate and cardiac arrest.


Theophylline is used to treat Asthma. It shares active ingredients with coffee, tea, chocolate and other high caffeine containing foods and beverages. Taking theophylline with those foods may significantly increase the risk of drug side effects such as nervousness, insomnia or tremors. On the other hand, grilled meats prevent the medication from working which can result in unmanageable asthma attack.

The perception of the non-invasiveness of natural foods and herbs is wrong. The only way to prevent possibly dangerous interaction of medicines and foods is to talk to your doctor and pharmacist and learn what kind of foods you should be careful about and what kind of side effects and symptoms you should be aware of. If you suddenly feel that something is wrong it is better to contact your doctor right away. Remember, it is always better be safe than sorry.