Grapefruit Interactions With Bipolar Drugs

Sliced grapefruit and glass of grapefruit juice on wood
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Grapefruit juice may seem like the ideal drink for a good, old-fashioned American breakfast, but when it comes to washing down your bipolar medications, think again. Unlike some types of citrus fruit, grapefruit can interfere with the metabolization of certain drugs, inadvertently increasing their concentration to potentially toxic levels.

Bipolar drugs are not the only ones affected. Also on the no-fly list are medications used to treat everything from high cholesterol and arrhythmia to allergies and HIV. Even Viagra is complicated by the otherwise healthy effects of grapefruit.

How Grapefruit Interferes With Drug Concentration

A number of psychotropic drugs, including those used treat anxiety, depression, and psychosis, are among the 85 agents grapefruit juice is known to interfere with.

This is because grapefruit contains furanocoumarins, an organic compound which blocks an enzyme that normally breaks down certain medications. While other citrus fruits like pomelos, limes, and Seville oranges also contain furanocoumarins, they haven't been studied as closely.

When this enzyme is blocked, the drug concentration levels in the blood will be higher than expected. In some cases, the intended effect and/or side effects of the drug will be stronger—even intolerable. In other cases, the interaction could be dangerous.

Degrees and Persistence of Effect

The degree by which grapefruit can affect certain drugs can vary. For some medications, one small glass of juice can result in what would be equivalent to a double or triple dose.

For example, as much as 99 percent of BuSpar (buspirone) is normally metabolized before the drug enters the bloodstream. When taken with grapefruit juice, the concentration can increase by as much as 400 percent

At the same time, the effects of grapefruit can be long-lasting, interacting with certain drugs anywhere from a few hours to 24 hours after ingestion.

With that being said, not all drugs in a drug class are affected (or affected in the same way) by grapefruit. For many bipolar medications, separating your grapefruit and daily dose by four hours is enough to avoid any interaction. 

Alternately, you can avoid grapefruit altogether and substitute with (non-Seville) orange juice. 

List of Psychotropic Medications Affected by Grapefruit

All told, there are 15 drugs commonly used to treat symptoms of bipolar disorder that are known to be affected, in differing degrees, by grapefruit.

  • Anafranil (clomipramine)
  • BuSpar (buspirone) 
  • Clozapine (clozaril)
  • Elavil (amitriptyline)
  • Halcion (triazolam)
  • Haldol (haloperidol)
  • Luvox (fluvoxamine)
  • Prozac (fluoxetine)
  • Seroquel (quetiapine)
  • Serzone (nefazodone)
  • Tegretol (carbamazepine)
  • Trazodone (desyrel)
  • Valium (diazepam)
  • Versed (midazolam)
  • Zoloft (sertraline)

Always read in the packet insert in its entirety to understand which interactions can occur. Typically, you can find this in or around the fifth paragraph where it would read: "Talk with your doctor before including grapefruit or grapefruit juice in your diet while you are taking this medicine." 

A Word From Verywell

Each year, an increasing number of drugs are identified as having a possible interaction with grapefruit. In the end, you can usually still enjoy the nutritional benefits of grapefruit if taken wisely. The combination of vitamin C, fiber, potassium, lycopene, and choline are key to maintaining a healthy heart and normalizing lipids (particularly triglycerides) in your blood. Speak with your doctor if in doubt.

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