Question: What kind of food should I avoid when I am taking medications?

Answer: Many patients wonder when starting a new medication: Can I still have my morning latte? Can I eat salad as I usually do? Or can I drink a glass of wine at the weekend’s family dinner? You have those questions because you heard some medications interact with certain foods, even the healthy foods. I am glad you ask, as some interactions can alter the body’s ability to utilize a drug or cause serious side effects. Medications must be taken properly to ensure they are effective and safe.

The foods to avoid depend on the type of medications and your medical conditions. Consult your pharmacists when starting a new prescription or over-the-counter (OTC) medications, and let them know your medical history to address your concerns better. Below I will introduce some of the common dangerous drug-food interactions.



Grapefruit and Grapefruit juice + Statins

Grapefruit and grapefruit juice can interfere with many types of drugs, in particular some statins. Grapefruit can increase the amount of statin in the body and causes more side effects such as muscle pain and damage. Patients should avoid eating grapefruit or drinking grapefruit juice while taking certain statins.

Here are additional examples of medication types that can be affected by grapefruit and grapefruit juice: certain blood pressure medications, some immunosuppressant medications for organ transplant, some medications for cancer treatment. To learn more, read Grapefruit Juice and Some Drugs Don’t Mix.



Vitamin K-Rich Food + Warfarin

Some vegetables such as kale, spinach, mustard greens, broccoli, and brussels sprouts are rich in vitamin K. A large quantity of Vitamin K can reduce the effectiveness of warfarin, which leads to a higher risk for blood clots. Patients on warfarin should maintain a consistent intake of these vegetables and avoid a sudden change in consumption. To learn more, read Warfarin Diet: What Foods Should I Avoid?



Alcohol + Metronidazole

Excess alcohol should always be avoided during sickness because it delays the recovery by weakening the immune system and dehydration. Alcohol also adversely interacts with countless commonly used prescription and OTC drugs leading potentially serious harm. For example, patients need to avoid alcohol while taking metronidazole and at least 72 hours after finishing the course. Otherwise, they might experience flushing, nausea, vomiting, headache, rapid heart rate, and liver damage. To learn more, read Harmful Interaction: Mixing Alcohol with Medicines.



Calcium-Rich Food + Antibiotics

Dairy products such as milk, yogurt, and cheese are rich in calcium, which can bind to certain antibiotics and prevent their abosprtion. When patients take antibiotics such as ciprofloxacin, levofloxacin, doxycycline, they should not take at the same time as dairy products. They can still have dairy products but need to be separated hours away from antibiotics. You also want to watch out for daily vitamins and antacids as they often contain calcium. To learn more, check Calcium Interactions.



Tyramine-Rich Food + Monoamine Oxidase Inhibitors (MAOIs)

MAOIs are effective antidepressants and can be used for treating other conditions such as Parkinson’s disease. Patients on MAOIs should avoid consuming food rich in tyramine, for example, cheese, beer, wine, cured meat, sauerkraut. MAOIs increase tyramine in the body and can cause dangerous side effects known as ‘Tyramine Reaction’ (headache, hypertension, flushing, fast heartbeat, nausea, stroke, death). To learn more, read MAOIs and Diet.


How do medical conditions affect food choices?

Even medicines might not directly interact with food; people with certain medical conditions should follow diets that help them stay healthier. Sometimes, keeping recommended diets are just as important as taking medications. For example, patients with hypertension should limit sodium, sweets, sugary drinks; patients with congestive heart failure should choose food low in salt; diabetic patients should avoid food high in fat, sugar, and sodium. As you can see, the foods to avoid while taking medications are individualized.


Fun fact!

Even though there are many dangerous drug-food interactions, sometimes we utilize the interactions to make the treatment more effective. For example, atovaquone/proguanil is a commonly used medication to treat or prevent malaria. This medicine is best taken with food or a milky drink that contains fat, which not only helps prevent upset stomach but also improves drug absorption.


How can you avoid drug-food interactions?

  • Listen to your pharmacist: as medication experts, your pharmacist will consult you on the potential drug-food interaction when you start new prescription medication.
  • Know your medical history and medication list: if you use more than one pharmacy, your pharmacist will need your help to get the full picture of your health.
  • Read the prescription label and package insert: always read the prescription label on the container carefully, which contains the direction, warning, and interaction precautions. The package insert is also a reliable resource for drug-food interaction.
  • Ask for help: contact your pharmacist or primary doctor if you are unsure about whether certain foods are safe to take while taking medications.


Prepared by Wenye Dang PharmD Candidate 2021