Food Risk: Drug Interactions

A number of medications do not interact with certain foods. For example, if antibiotics are taken at the same time as dairy products, they lose effectiveness. More than 300 medicines can become less effective or even toxic when taken with certain foods.

Drug interactions – facts and figures

Every German swallows an average of 1,250 tablets and other medications per year – and almost always without thinking about what they are swallowing them with, sometimes with milk, sometimes with coffee, sometimes even with beer, and quite often together with a complete meal. According to the German Pharmacists Association, more than 315 pharmaceutical substances react to food. These substances are found in more than 5,000 common medications. This means that 12.5 percent of medications can have undesirable side effects in combination with food. Doctors do not always give their patients dietary recommendations along with the prescription, which should be followed when taking the medication.

What are the possible drug interactions?

In most cases, however, the interaction is not too dramatic if, for example, you only occasionally swallow a headache medication. Patients and chronically ill patients who are administered up to ten different medications daily are considered at risk. This increases the risk potential immensely, reports the independent British Committee on Toxicity. Sometimes a drug simply doesn’t work as well when it enters the body together with certain foods. Occasionally, drugs block the absorption of important substances in the intestine, such as calcium, fluorine or iodine. In rare cases, drug-food interactions even threaten sleep disturbances and heart palpitations.

Common interactions with medications

Here are the most common effects of the most common medications.

Antibiotics and dairy products

Milk, cottage cheese, yogurt, and cheese and antibiotics don’t mix. The important drug group of tetracyclic antibiotics, such as doxycycline, can form compounds with the calcium from dairy products that the body cannot break down. This slows down the effect of the drug, so to speak. Calcium-containing foods such as milk and yogurt and Co. should therefore be consumed no earlier than two hours after taking these antibiotics.

Antibiotics and caffeine

Antibiotics containing gryase inhibitors are often prescribed for bladder or kidney infections. With caffeine, as contained in coffee, cola or tea, it can come to states of agitation, heart palpitations and sleep disorders, because the drug inhibits the breakdown of caffeine. Therefore, it is better to avoid caffeine completely while taking the drug.

Iron tablets and caffeine

Anemia medications are useless if swallowed together with coffee or tea. The tannic acid in the drinks binds the iron ions to themselves in the stomach. Thus, the iron is excreted instead of ending up in the bloodstream via the intestinal wall. Pregnant women, for example, who take their iron supplement with breakfast should not drink tea or coffee for at least two hours before and after taking the tablets.

Grapefruit juice and painkillers, sleeping pills, antihistamines, high blood pressure medications.

Completely avoid grapefruit juice when taking medications, even if some of the symptoms are rather rare. The flavonoids contained in it, which are the pigments contained in the plants, increase the effect of many drugs by about 30 percent and can, for example, trigger high blood pressure. This also applies to bitter oranges, which are contained in some orange jams and marmalades.

Licorice and diuretics

Diuretics are agents that dehydrate the body. At the same time they flush out vitamins and minerals. If licorice lovers take diuretic drugs over a long period of time, there is an increased loss of potassium.Symptoms: Muscle weakness, drowsiness, weaker reflexes and elevated blood pressure.

Asthma medication with theophylline and black pepper.

Pharmaceutical manufacturer Madaus warns that those who like spicy black pepper should be especially careful, because the piperine it contains inhibits the breakdown of theophylline, which is prescribed mainly for severe bronchial asthma. In fact, one study found that piperine can increase theophylline levels. These patients should also avoid foods or medicines containing tannin. Foods containing tannin include black tea, green tea, walnut, raspberry, oak, and witch hazel.

Antidepressants and wine or cheese, respectively.

Antidepressants often contain so-called MAO inhibitors. These inhibit the enzyme monoamine oxidase (MAO), which breaks down certain neurotransmitters. In this way, MAO inhibitors increase the concentration of various neurotransmitters in the brain, to put it simply: in this way, they ensure that more of the happiness-enhancing neurotransmitters serotonin, norepinephrine and dopamine are available in the brain. The mood enhancers come into conflict with protein- and tyramine-containing foods that are stored for a longer period of time. This includes sauerkraut, cheese, white beans as well as salty herrings. The protein product tyramine cannot be broken down in the body during ingestion because the enzyme essential for this process does not work. If cheese and wine – especially Chianti – are taken together with MAO inhibitors, this can trigger life-threatening high blood pressure crises and cerebral hemorrhages. Bananas and pineapple, nutmeg, figs, raisins, yogurt, soy sauce, and sauerkraut are also considered potentially dangerous.

Unproblematic: anticoagulants and green-leaf vegetables.

According to recent studies and contrary to much information, commonly prescribed blood thinning agents, so-called anticoagulants such as Marcumar, to prevent thrombosis, for example, are considered unproblematic. Vitamin K is found in green leafy vegetables (cabbage, spinach, kohlrabi, lettuce, sauerkraut ) as well as in liver, meat and egg. There is no need to avoid such vitamin K-containing foods, writes the German Nutrition Society (DGE): “In a series of clinical studies, it has been demonstrated that even by consuming larger amounts of vitamin K-rich foods, the Quick value is not or only insignificantly affected. For patients undergoing anticoagulation therapy with vitamin K antagonists, there is therefore no reason to avoid vitamin K-rich foods, such as liver, spinach, broccoli, white, red, green and cauliflower.” It makes sense, however, to avoid appropriate multivitamin preparations or their intake should be clarified with the attending physician.

Tips for taking medicines

On the package inserts, you will find the instructions on when to take the medication. If it says “take before meal,” then the medicine should be taken 60 to 30 minutes before the meal. “Taking during a meal” means taking within five minutes of the meal. “Taking after meal” means there should be an interval of 30 to 60 minutes between meal and taking. Medication should always be taken with sufficient liquid, preferably pure water. Alcoholic beverages should always be avoided if you have been prescribed medication. In the case of tranquilizers or blood pressure medication, the effect can be intensified: Alcohol also promotes the absorption of the medication and increases its effectiveness. It is therefore essential to heed the warnings on the package inserts of medications, since even a small amount of alcohol can greatly reduce the ability to react. It is best not to drink fruit juices and soft drinks until half an hour after taking the medication. In the case of antibiotics, at least two hours should elapse between taking the medication and drinking milk. Also, with iron supplements, do not consume milk, cream, rhubarb or protein-rich products.

Ask the doctor or pharmacist

Most people, however, have little need to adjust their diets when taking medications, the Committee on Toxicity report balances. Numerous drug interactions, such as reduced effectiveness of antibiotics when consumed at the same time as dairy products, are described on most drug instructions for use. However, the experts strongly advise people to read the directions for use carefully under the heading “Drug Interactions” before taking any medication.In case of doubt, the pharmacist should be consulted, especially in the case of non-prescription drugs. Physicians should obtain accurate information about their patients’ dietary habits before prescribing medications.