Grapefruit: benefits, dosage, contraindications

Mis à jour le 7 November 2025

The grapefruit originates from Southeast Asia and became popular in Europe in the 18th century. It is the result of a natural cross between the sweet orange and the pomelo. Grapefruit seed extract (GSE) is a concentrate obtained from the seeds and the white membranes of the fruit, known for its many therapeutic properties. Grapefruit is rich in vitamin C, flavonoids (notably naringin), and antioxidants, which give it beneficial health properties. GSE also contains polyphenols, known for their powerful antimicrobial properties. Grapefruit has antioxidant properties, mainly thanks to the flavonoids it contains. Grapefruit seed extract is recognized for its effectiveness against a wide range of bacteria, viruses, and fungi, including resistant pathogens. The fruit's vitamin C stimulates the immune system and strengthens the body's ability to fight infections. GSE is used in the form of drops or capsules to prevent and treat various digestive, skin, and ENT infections. For external use, it is effective against fungal infections and skin irritations.

Scientific name(s)

Citrus paradisii

Family or group:

Plants

Active ingredients:

Naringin

Neohesperidin

Bioflavonoids

Apigenin

Indications

Scoring methodology

EFSA approval.

Several randomized, double-blind, controlled clinical trials (> 2), including a significant number of patients (>100), with consistently positive conclusions for the indication.

Several randomized, double-blind, controlled clinical trials (> 2), including a significant number of patients (>100), with positive conclusions for the indication.

One or more randomized studies, or several cohorts or epidemiological studies, with positive conclusions for the indication.

Clinical studies exist but are uncontrolled, with conclusions that may be positive or conflicting.

No clinical studies to date that can demonstrate the indication.

Oral and Dental Infections
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Grapefruit seed extract (GSE) is sometimes used as a supplement in the treatment of oral and dental infections due to its antibacterial and antifungal properties. It may reduce the bacterial growth responsible for gingivitis and bad breath. As a mouthwash (diluted), it acts as a natural antiseptic, limiting inflammation and improving oral hygiene. However, robust clinical studies are lacking to confirm its effectiveness for these indications, and its use does not replace conventional treatments.

Posologie

By mouth: seeds

grapefruit seed extract

Fungal infections
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Grapefruit seed extract (GSE) is known for its antifungal properties, particularly against Candida albicans and Aspergillus niger, which are responsible for skin fungal infections. Used topically in a diluted form, it may relieve superficial infections such as athlete's foot by inhibiting fungal growth.

Posologie

Topical use: seeds

grapefruit seed extract

Properties

Antimicrobial

GSE is particularly valued for its antibacterial, antiviral, and antifungal properties. Its flavonoids, such as naringin and hesperidin, act by destroying the membrane of pathogenic microorganisms, which inhibits their reproduction. Studies show its effectiveness against Escherichia coli, Candida albicans, Staphylococcus aureus and even some enveloped viruses. Unlike synthetic antibiotics, GSE preserves the beneficial intestinal flora while eliminating pathogens.

Usages associés

Oral and dental infections, fungal infections

Grapefruit Seed Extract as a Natural Derived Antibacterial Substance against Multidrug-Resistant Bacteria
Anti-Biofilm Activity of Grapefruit Seed Extract against Staphylococcus aureus and Escherichia coli

Safe dosage

Adult: 10 drops - 15 drops

Grapefruit seed extract (GSE) is generally used as a liquid solution or in capsules. For an adult, the standard dosage is 10 to 15 drops diluted in a glass of water, 2 to 3 times a day, for a duration of 7 to 15 days. nnFor external use, GSE is diluted in water or a vegetable oil before being applied to the skin to treat fungal infections or irritations. The concentration varies according to needs, but a dilution of 5 drops per 50 ml is often recommended for safe application.nn

Interactions

Médicaments

Cytochrome P450 3A4: strong interaction

Grapefruit and grapefruit seed extract (GSE) are well known for their potential interactions with certain medications. These interactions are primarily due to the inhibition of hepatic enzymes, notably CYP3A4, which plays a key role in the metabolism of many drugs. This inhibition can lead to increased plasma concentrations of the affected drugs, thereby amplifying their effects and their risk of side effects.nnThe classes of drugs most affected include statins, immunosuppressants, calcium channel blockers (for hypertension), and certain anxiolytics. Even in small amounts, grapefruit can prolong the half-life of medications or alter their elimination.

Precautions

Pregnant women: use with caution

The use of GSE is not formally contraindicated, but it is advisable to seek medical advice before consuming it. nn

Breastfeeding women: use with caution