What is a drug-food interaction?
A drug-food interaction happens when the food you eat or drink affects the ingredients in a medicine you are taking so the medicine can't work the way it should.
Drug-food interactions can happen with both prescription and over-the-counter medicines, including antacids, vitamins and iron pills.
How does grapefruit interact with medicines?
Eating grapefruit or drinking grapefruit juice affects how your body metabolizes (processes) certain medicines. The chemicals in grapefruit keep certain enzymes that normally process medicines from working correctly, which can cause higher levels of some medicines in your body. This makes it more likely that you will experience side effects from the medicine. Certain types of oranges, such as pomelo and seville, can also cause similar effects.
Interactions can happen up to 3 days after eating or drinking grapefruit. This means you cannot drink grapefruit juice in the morning and take your medicines later in the day to stop possible medicine interactions.
Do all medicines interact with grapefruit?
Only some medicines interact with grapefruit. Examples include medicines for:
- High cholesterol: atorvastatin, lovastatin and simvastatin
- High blood pressure: felodipine, nifedipine, nimodipine and nisoldipine
- Heart arrhythmia (a condition that occurs when your heartbeat is abnormal): amiodarone
- Depression: buspirone and sertaline
- Human immunodeficiency virus (HIV): saquinavir
- Suppressing the immune system (often prescribed to help people who have recently received organ transplants): cyclosporine and tacrolimus
If you don't know if the medicine you are taking interacts with grapefruit, ask your doctor or pharmacist. Your doctor can usually prescribe another medicine that doesn't interact with grapefruit.
Do all fruit juices interact with medicines?
Grapefruits, pomelo oranges and seville oranges are the only fruits known to cause interactions with medicines. All other fruit juices, even other citrus juices, are safe to drink when taking medicine. There is no proof that these other juices interact with medicines.
What if I take a medicine that interacts with grapefruit?
An interaction can occur even if you eat or drink a small amount of grapefruit. However, if you like grapefruit and want to continue to enjoy it, ask your doctor if there is a different medicine for you that doesn't interact with grapefruit.
Written by familydoctor.org editorial staff