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Food and Drug Interactions: An Inside Story
Eating when taking some meds may help you tolerate them better. But many foods can dangerously raise or lower drug levels in your body.

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Food and Drug Interactions: An Inside Story

What you eat and drink can affect the way your body uses medications. Some food and drink can make some drugs less effective, and others can cause some drug levels to build up too high in your body.

Below are some types of foods and drink that can interact with drugs:

Grapefruit and grapefruit juice
This fruit (and similar fruits*) can raise the level of many medications, which can lead to side effects. Here is a partial list of those medicines:

  • Cholesterol-lowering statin drugs
  • Drugs that treat high blood pressure, irregular heartbeat and other heart conditions
  • Drugs that treat immune system conditions
  • Certain HIV drugs

Seville oranges and tangelos can have a similar effect on drugs as grapefruit. However, not all citrus fruits - like lemons, limes, tangerines and oranges - cause the same problems. Ask your doctor or pharmacist if the medicine you take may be affected.

Calcium: milk, yogurt and dairy products, and calcium supplements
Certain drugs, such as some antibiotics, should not be taken at the same time as dairy products. It is recommended that you take these drugs at least two hours before consuming milk or dairy.

Foods high in vitamin K
Vitamin K helps in blood clotting. It is found in green leafy vegetables like spinach, kale and collards. It's important to eat about the same amount of vitamin K-rich foods if you take the blood thinner warfarin. If you have changed your diet recently, you may need to have you blood tested to make sure your medication is at the right dose.

Caffeine is a stimulant drug that may be found in some coffees and teas, some sodas, energy drinks and chocolate. Too much can lead to side effects such as a fast heartbeat and nervousness. Caffeine can also affect how other drugs work (such as medications to help you sleep).

If you are taking the heart medication digoxin, licorice may increase the amount of drug in your body to problem levels. Licorice can also make some blood pressure drugs less effective.

Potassium-rich foods
Some foods - like bananas, oranges, and green leafy vegetables - can increase your potassium level. Some types of diuretics and blood pressure medications can also cause potassium to build up in your blood. Your doctor may advise you to cut back on foods with potassium if you are taking certain medications.

If you are taking any sort of medication, it's recommended that you avoid alcohol. Alcohol can increase or decrease the effect of many drugs. For example, using acetaminophen with alcohol may increase the risk of liver damage .

Chocolate (along with other foods such as cheeses, salami, red wine and bananas) contains a compound called tyramine. Eating foods rich in tyramine while taking some medications, such as MAOI antidepressants, may cause a dangerous increase in your blood pressure.

Vitamins, minerals and supplements
The vitamins and minerals found in our foods can be taken separately as tablets or capsules. This is also true for the many dietary supplement products available. These can interact with your medications too, so it is important to always tell your doctor or pharmacist if you take vitamins, minerals or supplements.

To sum up, the following may help to cut your risk for food and drug interactions:

  • Read the label on every medication you take.
  • Ask your doctor or pharmacist what you need to avoid when prescribed a new drug.
  • Keep an up-to-date list of all prescription drugs, over-the-counter drugs, and supplements you can share with your providers.
By Susan G. Warner, Contributing Writer
Created on 04/14/2009
Updated on 11/05/2014
  • U.S. Food and Drug Administration. Avoiding drug interactions.
  • U.S. Food and Drug Administration. Avoid food-drug interactions: A guide from the National Consumers’ League and US Food and Drug Administration.
  • U.S. Food and Drug Administration. Drug interactions: What you should know.
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