Food-Drug Interaction

Submitted by Dr Becky Wise

Normally when we hear the term “drug interactions” most of us think of how one medication can interact with another, or how that medication can affect another condition that we may have. However, have you ever stopped to think about how the things that we eat and drink can affect the way our medications work as well?

A drug-food interaction happens when the food you eat affects the ingredients in a medicine you are taking so the medicine cannot work the way it should. This can be anything from the medication not being able to work in the way that it should to it resulting in a new side effect of the medication.

With any medication that you take, it is important to know how to take it in regards to food. Should it be taken with food or without? Or should it be taken before a meal? If so, how long before? Are there any foods that it shouldn’t be taken with? These are all questions that you need to know the answer to before taking any prescription or over the counter medications. Some medicines can work faster, slower, better, or worse when you take them on a full or empty stomach. For example, taking some medicines at the same time that you eat may interfere with the way your body absorbs the medicine. The food may delay or decrease the absorption of the drug. On the other hand, some medicines will upset your stomach, and if there is food in your stomach, that can help reduce the upset.

Some bottles may specifically say to take the medication "with food", or "on an empty stomach".
Some bottles may specifically say to take the medication “with food”, or “on an empty stomach”.

One place to find this information would be on the prescription label. Some bottles may specifically say to take the medication “with food”, or “on an empty stomach”. You may also be able to find this information in the prescription monograph that is given to you when you pick up your prescription. However, the easiest way is to just check with your doctor or pharmacist, especially when starting a new medication.

In addition to being affected by the presence or lack or food in general, some medications may also interact with specific foods or food groups . Several of the most common drugs that are significantly affected by specific foods are discussed below:

Warfarin (Coumadin) blood thinner: Foods that are high in vitamin K such as green leafy vegetable make warfarin work less effectively at thinning your blood. A diet high in vitamin K may require you to take larger doses of warfarin on a daily basis. This is okay as long as you stay consistent in the amounts of these foods you eat daily. These foods are most dangerous when you suddenly start to consume much more or much less than normal. Sudden changes in your diet may require more frequent INR testing

“Statin” medications for high cholesterol such as Simvastatin (Zocor), Atorvastatin (Lipitor), and Rosuvastatin (Crestor): Grapefruit and grapefruit juice inhibits the metabolism of statin medications which can increase the amount of the medication in your body. This can lead to side effects such as muscle pain and fatigue. A small amount of grapefruit may be okay on a regular basis as long as you stay consistent. Sudden changes in your eating habits could lead to unwanted side effects.

Levothyroxine (Synthroid) for hypothyroidism: Levothyroxine is best absorbed by your body on an empty stomach. It is best to take this drug in the morning, on an empty stomach, at least 30 minutes before eating. Foods that contain calcium (dairy products , tums antacids) or are high in fiber should be avoided for longer (several hours) to avoid interactions

The key to preventing these food-drug interactions is consistency. Almost any food is fine in small amounts as long as you are eating the same things on a regular basis. Always talk to your doctor or pharmacist before making any sudden or severe changes to your diet to make sure this won’t affect the way any of your medications work.

Remember, taking your medications properly is a key part in maintaining your health. This includes knowing what medications should be taken with and without food, as well as knowing what specific foods can and cannot be eaten with each medication. Always ask your doctor or pharmacist about possible food-drug interactions before starting a new medication and before making any sudden changes to your eating habits. Be an advocate for your own health. If you are ever unsure about how to take a medication ASK. Your doctor and pharmacist are happy to help; it’s what they are there for!

For further reading:
Written by Lauren Altmeyer, PharmD Candidate, LECOM School of Pharmacy Class of 2015

Be Well, Be Wise,


Dr. Rebecca Wise

Wise Words…. is a general medical information column from Dr Rebecca Wise. Dr. Wise has a master’s degree in education as well as her doctorate in pharmacy. She is an assistant professor and ambulatory care specialist at a Medication Therapy Management (MTM) clinic in Erie, PA.

Soon to be released is Dr Becky’s new website which will address women’s issues, watch for it:

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