When taking medications it is essential to know what risks exist in combination with food and beverage intake. As a general rule, package inserts refer to the dangerous effects of drinking alcohol with a medication prescription in progress, but there are also risks with other products that do not contain alcohol. One of the most striking cases is that of grapefruit, which in both fruit and juice format (the most common), is associated with harmful health consequences if combined with certain medications.
Grapefruit is a fruit that stands out in the field of nutrition for its healthy properties. In this sense, it is a source of fiber, key for the proper functioning of the digestive tract; it has a lot of potassium, an essential mineral for the proper functioning of the body; and it provides a large amount of vitamin C, necessary for the normal growth and development of the human body. However, the U.S. Food and Drug Administration (FDA) warns about its dangers with certain medications.
According to this US government agency, these are the drugs that can cause problems if they interact with grapefruit or grapefruit juice in our body (the generic name is included in parentheses):
- Cholesterol-lowering drugs such as Zocor (simvatastine) and Lipitor (atorvastatin).
- Medications to treat hypertension such as Procardia (nifedipine) and Adalat CC (nifedipine).
- Drugs to prevent organ transplant rejection such as Neoral (cyclosporine) and Sandimmun (cyclosporine).
- Anti-anxiety drugs such as Buspar (buspirone).
- Drugs that treat Crohn’s disease or ulcerative colitis such as Entocort EC (budesonide).
- Drugs that treat abnormal heartbeat such as Pacerone (amiodarone) and Cordarone (amiodarone).
- Antihistamine drugs such as Allegra (fexofenadine).
Grapefruit juice does not affect all of the above generic drugs. The severity of the interaction may be different depending on the person, the drug and the amount of juice taken.
Grapefruit juice allows too much of the drug to enter the blood or, in other cases, too little. “When there is too much medication in the blood, you can have more side effects,” explains Shiew Mei Huang, an FDA physician.
For example, if you drink too much grapefruit juice with cholesterol-lowering drugs, too much could remain in the body, increasing the risk of liver and muscle damage, and even leading to kidney failure.
Also, many drugs are broken down (metabolized) in the small intestine with the help of the CYP3A4 enzyme. Grapefruit juice can block the intestinal action of CYP3A4, so instead of being metabolized, more of the drug enters the blood and spends more time in the body.
The amount of CYP3A4 in the intestine varies among people. Some people have too much and others too little. Therefore, grapefruit juice may affect differently, even in people taking the same medication.
On the other hand, antihistamine medications such as fexofenadine have their blood levels reduced by grapefruit juice. This may cause the medication not to work as it should.