Function

Substances found in grapefruit juice can prevent the body from breaking down certain types of statins in the liver, so they build up to high levels in the blood and can, in effect, cause an overdose.

Types

At least one study, published in the journal Clinical Pharmacology and Therapeutics, found that only some types of statin medications are affected by consumption of grapefruit and only in certain amounts. Your doctor can tell you if you can eat grapefruit while taking a particular statin drug.

Time Frame

Grapefruit juice consumed at the same time as some statin medications can interfere with the breakdown of the medication for at least three days.

Considerations

Grapefruit may not affect statin mediations if the two are consumed at different times of the day, according to Mayo Clinic cardiologist, Dr. Gerald Gau, M.D.

Warning

Red yeast rice is an alternative cholesterol-lowering medication which acts like a statin in the body. You should avoid eating grapefruit or grapefruit juice if you take red yeast rice supplements, according to University of Maryland Medical Center.