Statins are prescription drugs used to lower cholesterol. They prevent your body from making more cholesterol and can help your body reabsorb the cholesterol already present in your artery walls.

Not everybody with high cholesterol levels needs to take statins. The drug is recommended for people who are at a high risk for heart disease. Individuals with a family history of heart disease and high cholesterol might need to take statins.

Other risk factors such as being overweight or having diabetes might warrant statin use as well.

The secret to the interaction between grapefruits and statins is in furanocoumarins, according to a study published in the American Journal of Clinical Nutrition. Furanocoumarins are organic chemical compounds present in many different plants, including grapefruit.

Not all statins interact in the same way with grapefruit. The interaction is particularly strong with two types of statins: simvastatin (Zocor) and atorvastatin (Lipitor). If you’re taking a different type of statin, ask your doctor about the risk of interaction.

The interaction between grapefruit and medications poses dangers only if you’re taking the drug orally, because the interaction occurs in your digestive tract. If you use a skin patch or receive your medication through an injection, you may have a lower risk of adverse effects.

When mixing grapefruit and statins, there is a chance of increased side effects.

Women and people over 65 are at a higher risk of developing side effects from statins. These side effects include:

  • muscle breakdown
  • liver damage
  • digestive problems
  • increased blood sugar
  • neurological side effects

Milder side effects include muscle and joint pain.

The FDA reports that the risk of muscle breakdown and liver damage can lead to kidney failure. Neurological side effects include confusion and memory loss, according to the Mayo Clinic.

The exact amount of grapefruit it takes to have a negative reaction with statins is unknown. Just one grapefruit or one glass of grapefruit juice could be enough to cause an interaction with some medications. Both fresh and frozen juices have the same effect.

Other studies have suggested that grapefruit in moderation showed no ill effects. Most cases of a problem involved consuming large amounts.

If you accidentally consume a small amount of grapefruit, it isn’t likely to affect your medication. However, it’s best to check in with your doctor for any ill effects, since it’s unclear how common these interactions are.

No two people have the same reaction when mixing grapefruit and statins.

To be safe, restrict drinking and eating grapefruit if you take statins until you talk to your doctor about the risk. It’s also recommended to avoid grapefruit juice when taking medication.

There are several other citrus fruits that might affect statins. The list includes tangelos, pomelos, bitter oranges, and Seville oranges.

There have been no documented problems with lemons, tangerines, clementines, mandarins, navel oranges, and blood oranges.

It’s not only statins and grapefruit that don’t mix. A number of other medications also shouldn’t be taken with grapefruit. These include many drugs used to treat blood vessel and heart conditions.

Grapefruit also interacts with drugs used to treat nausea and urinary tract infections, antirejection drugs, medications to treat cancer, and many drugs that affect the central nervous system, including antianxiety drugs.

According to the FDA, grapefruit might also affect your body if you’re taking allergy medication, such as fexofenadine (Allegra).

The furanocoumarins suppress the ability of an important enzyme. This enzyme normally helps your body process the medication you take, balancing out how much of it goes into your bloodstream. The furanocoumarins hinder this enzyme, creating larger amounts of the drug in your bloodstream.

Although grapefruit interacts with over 85 medications, not all of the interactions cause serious side effects. Sometimes grapefruit interacts with only some of the drugs in a category, not all.

For example, you might need to stop taking Zocor or Lipitor, but you might be able to take a different statin.

If you have doubts or questions, talk to your doctor about the risks of mixing medications and grapefruit.

Q:

If I have a grapefruit or glass of grapefruit juice, is there a safe amount of time I should wait before taking my medication or vice versa?

A:

The effect of grapefruit juice on some drugs may last longer than 24 hours and avoiding drinking any grapefruit juice is wise advice. Eating half a grapefruit is probably less risky because it contains a relatively small amount of juice but could still have an effect. To be safe, check with your doctor if you take one of the two statins mentioned above.

Alan Carter, PharmDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.