Taxonomic Class

Rutaceae

Common Trade Names

Citricidal, GSE, Traveler’s Friend

Common Forms

Liquid extract

Source

Grapefruit seed extract is synthesized from the pulp, seed, and inner rind of the fruit of Citrus paradisi.

Chemical Components

The liquid concentrate contains 67% vegetable glycerin (derived from palm and coconut) and 33% CitricidaI. Traveler’s Friend is made up of 67% deionized water and 33% Citricidal.

Grapefruit juice contains naringin and naringenin, which inhibit the production of CYP3A4, leading to increased rates of absorption of certain drugs. Grapefruit seed extract contains about 0.1 % of these compounds.

Actions

Grapefruit seed extract is part of the quaternary compound, and its structure is similar to that of benzylkonium chloride. The extract is reported to exhibit antibacterial, antifungal, and, potentially, antiviral activity. One study of the antimicrobial efficacy of six grapefruit seed extract products found that the preservative agents in the products, including benzethonium chloride, triclosan, and methyl parabens, were responsible for their activity.

Reported Uses

Grapefruit seed extract has been used topically as an antiseptic wound cleaner and to treat skin infections and internally as supportive treatment for various ailments, including Candida infections, GI upset, and sore throat. Grapefruit seed extract has also been used by campers and travelers to foreign countries to purity drinking water.

Dosage

One product reports a dosage of 10 to 15 gtt P.O. in water or juice b.i.d. or t.i.d.

Adverse Reactions

GI: indigestion.

Interactions

Anticonvulsants, benzodiazepines, calcium channel blockers, certain antibiotics and antivirals, cyclosporine, nonsedating antihistamines, oral contraceptives, quinidine: Grapefruit extract may increase the bioavailability of these classes of drugs by inhibiting the cytochrome P-450 isoenzyme in the liver and gut wall . Monitor the patient closely.

Contraindications And Precautions

Avoid using grapefruit seed extract in pregnant or breast-feeding patients; effects are unknown. Do not use in the eyes. Do not use the extract with a mechanized toothbrush or tooth polisher because the acidic nature of the extract and abrasive actions of these instruments could cause tooth damage, including enamel erosion.

Special Considerations

Grapefruit seed extract concentrate has a pH of 2.2 and should be diluted before use.

The extract is extremely bitter.

Advise the patient to consult a health care provider before using herbal preparations because a treatment that has been clinically researched and proved effective may be available.

Points of Interest

The U.S. Department of Agriculture (USDA) confirmed that Citricidal was effective in inhibiting viral strains in cattle and hogs in the early 1980s and approved it for use in the USDA’s Evian Influenza Eradication Program in 1984.

Commentary

Although grapefruit seed extract has been thought to be effective as an antimicrobial, limited studies have not supported this claim. Further investigation is needed into whether grapefruit seed extract alone possesses antimicrobial activity or if it lies with the product’s preservative.

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