Interactions Between Food and Drugs

When we see the need or obligation to take any medication to cure, we must bear in mind that the food we eat can have some effect on these drugs. In some cases these effects will be positive, increasing drug efficacy or helping to reduce side effects, but sometimes the effects can be negative and even cause the drug to lose effectiveness.

For this reason, it is important to know the possible interactions between food and medicine, as well as how to take a certain drug. We will also request information to the physician or, failing that, the pharmacist about whether we have to take the drug with meals or fasting in order to get the best result possible.

Not usually pay much attention to these interactions and are quite common. In particular, care must be taken in those patients taking medications with a narrow therapeutic index drugs or those chronic use.

In these food-drug interactions influenced by three types of factors: those that depend on the patient, medication and food.

– Patient-dependent factors: Depending on age, sex, general health and physiological effects of the drug may vary.

– Dependent on food factors: They are essential proteins and carbohydrates that are ingested in the diet, the fat content and total fluid intake are key when considering the interactions between food and medicine.

– Factors dependent on the medicine, will depend on the characteristics and components of the drug.


This type of interactions that occur between food and drugs could be divided into two types:

– Modification pharmacodynamics: though in smaller numbers, are the most serious since they affect the action of the drug itself.

– Altered pharmacokinetics: is the most common and occurs when foods alter absorption, distribution or drug metabolism.

There may be a large number of interactions between food and medicine, but the most common are:

– Fatty foods reduce absorption and effects of antiretroviral drugs even halfway.

– Milk and iron absorption and reduce the effects of fluoroquinolones and bisphosphonates.

– The protein-rich foods cause a reduction in absorption of ulcer.

– Garlic in high doses reduces the bioavailability of antiretroviral drugs to significantly reduce its absorption.

– The cruciferous vegetables (cauliflower, cabbage, broccoli …) reduce the effectiveness of oral anticoagulants.

– Citrus juices, especially grapefruit, increase plasma levels of antagonists of calcium channel blockers, anti-rejection drugs for transplant, triazolam and saquinavir.

– Soy increases plasma levels of drugs and their side effects.