The foods you eat can affect how your body reacts to certain medications. Although grapefruit can be dangerous if it interacts with some medications, it does not appear to interact with hydrochlorothiazide, a diuretic often used to treat high blood pressure. However, ask your doctor about eating grapefruit if you take any medications.
Grapefruit and Cytochrome p450
Consuming grapefruit or grapefruit juice can be dangerous if you take some medications. This is because grapefruit affects the activity of some important enzymes in your liver. Cytochrome p450 is a group of related proteins that break down different molecules in your blood, including some prescription drugs. One of the effects of grapefruit juice is that it decreases the activity of this enzyme.
Grapefruit and Medications
Because grapefruit can interfere with the activity of cytochrome p450, it may also alter the way your body breaks down different medications. Some drugs, including the calcium channel blocker class of blood pressure medications, are metabolized by cytochrome p450, so inhibition of this family of enzymes can cause increased levels of the drug in the blood. This can cause an accidental overdose. However, grapefruit does not appear to affect hydrochlorothiazide, meaning you can consume grapefruit while taking this medication.
To understand why grapefruit does not interact with hydrochlorothiazide, you need to understand how this medication is eliminated from the body. Hydrochlorothiazide binds to different proteins in your blood, but does not undergo significant chemical changes. Hydrochlorthiazide is primarily excreted from your body in the urine, and approximately 95 percent of the drug excreted in the urine is found as unchanged drug. Because hydrochlorothiazide is not broken down by your liver, grapefruit does not affect this drug.
Although grapefruit will not increase your risk of developing side effects from hydrochlorothiazide, taking this medication along with any food, including grapefruit, can decrease its absorption, limiting its effectiveness. Consequently, hydrochlorothiazide should always be taken on an empty stomach. Talk to your doctor if you eat grapefruit regularly, because it may interfere with other medications that you take, including other blood pressure medications.