Food, drinks, supplements interact with medications

Alaska Med Ed

November is Thanksgiving month, a time when we reflect on our blessings and often celebrate them with food and drink — so it is also a good month to think about the tricks your food and drink can play on your medicines, like leftover Halloween pranks.

Here are a few food-and-drug facts worth reflecting on:

There are 249 drugs that interact with grapefruit juice. Grapefruit juice can interfere with how the body metabolizes (takes up and processes) medication. When medicine isn’t passing through and out of your system, it can build up, increasing the risk of side effects. This can last up to three days after eating grapefruit or drinking grapefruit juice.

The pH (how acidic a substance is) of the stomach is important because that’s where many drugs dissolve into their usable form — which is why some drugs need to be taken on an empty stomach. (To be sure a drug is processed on an empty stomach, take it an hour before you eat, or two hours after you eat.)

I hope that’s convinced you to be mindful as to whether there are foods you should avoid when taking one of your medicines. But in case you need more persuading, here are more interactions with foods, herbs and alcohol, and how they can make your medicine less effective, or exaggerate its effects.

Your body will have a hard time using your Warfarin if you take it while eating an avocado, because high-fat foods prevent it, and many other drugs, from being absorbed.

Dairy products, including milk, cheese and yogurt, can bind with certain drugs, such as antibiotics, which also interferes with absorption. Similarly, dark green vegetables and other foods with a lot of vitamin K can decrease the effects of blood thinners.

Cheese, alcohol, caffeine and red wine all mimic the actions of certain drugs.

Alcohol gets special mention because if we indulge a little, and have done so all our adult lives, we think we know how it affects us. But like a character in a mystery movie who is revealed as having a hidden identity, alcohol’s effects change with time. The human body metabolizes things differently at different life stages, and alcohol has a stronger effect in senior years than in middle age. When mixed with medications, even a little bit of alcohol can cause drowsiness, dizziness and increase your risk of falling.

Herbal supplements are another seemingly harmless source of interactions that can be quite serious. Some common examples:

• St. John’s Wort affects heart medications and antidepressants.

• Gingko biloba can exaggerate the effects of blood thinners.

• Kava can cause liver damage.

• Yohimbe can cause problems with blood pressure and the heart.

• Psyllium can interfere with heart and blood pressure medications and affect blood sugar levels in diabetics.

• Valerian can increase the effects of sedatives and other antianxiety medications.

• SAMe can have an additive effect when mixed with antidepressants and narcotic pain relievers.

This is not a complete list of herbs with side effects. Be sure to tell your prescriber and/or pharmacist about any herbal supplements you’re taking.

If you already take medications, check with your provider before adding an herbal supplement to your regimen.

Also keep in mind that herbal supplements are not well regulated, and products may contain very little of the “active ingredient.”

So to keep your medicines working like a treat (with no tricks!), read the labels on your medications carefully for advice about foods. If you have a question, thankfully you can ask a pharmacist or your health care provider.

Have a question or want a medication adherence goodie? Email me

If you have a question about medications you’d like answered, or if you’d like us to send you a seven-day pill dispenser, wallet-sized medication list card, or small, flat, bendable magnifying glass, email us at

Lana Bell is a state pharmacist for the Alaska Pioneers’ Homes.