Why You Should Exercise Caution With Grapefruit Seed Extract

Grapefruit seed extract is made from the seed, pulp, and membranes of grapefruit. The extract is ground down and then combined with glycerin. Grapefruit seed extract (GFSE) should not be confused with grapefruit seed oil or grape seed extract (GSE).

The extract has been marketed as having antibacterial and anti-inflammatory properties with several health benefits. However, many claims about its benefits remain unfounded.

Importantly, there is a history of commercial GFSE products being contaminated with synthetic antimicrobial compounds that can be harmful in large amounts. Keep this in mind when deciding whether to purchase GFSE supplements.

This article will review GFSE supplements, including the potential risks and what to consider.

Pile of grapefruits

Getty Images / Alexander Spatari

What the Research Says About Grapefruit Seed Extract

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

There are claims that grapefruit seed extract can be used to treat fungal or bacterial infections. It has been shown to have some antibacterial properties.

Many GFSE products have been found to be adulterated with the preservative benzethonium chloride, an antibacterial agent. Lab studies have indicated that the benefits related to GFSE have been due to the synthetic antibacterial agent.

However, there is no research to support any of the health claims about GSFE. In fact, there are no prospective randomized clinical trials on the effects of consuming GFSE alone in humans.

Precautions

There is not a lot of information available on the safety of GFSE. Also, bear in mind there have been reports of synthetic additives in commercial GFSE products that are not listed on the product's label.

It would be best to avoid supplements that lack safety data for pregnant and nursing individuals and children. You should also not use GFSE if you have a citrus allergy.

Speak to your primary care provider, pharmacist, or a registered dietitian nutritionist (RDN) if you are considering GFSE . They may be able to recommend alternative remedies that have fewer risks or an over-the-counter or prescription treatment, depending on your needs.

Dosage: How Much Grapefruit Seed Extract Should I Take?

There is no standard dose recommended for GFSE.

Given the lack of the research on this particular supplement, doses used in research studies are also not available.

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

Grapefruit Interactions

Grapefruit is known to interact with several medications.

Medications with grapefruit interactions include but are not limited to:

  • Pacerone and Cordarone (amiodarone)
  • Some antihistamines, such as fexofenadine and terfenadine
  • Benzodiazepines, such as Xanax (alprazolam)
  • Blood thinners, such as Plavix (clopidogrel) and Brilinta (ticagrelor)
  • Buspirone
  • Calcium channel blockers, such as Cardizem (diltiazem) and Verelan (verapamil)
  • Tegretol (carbamazepine)
  • Immunosuppressants, such as Prograf (tacrolimus) and Neoral or Sandimmune (cyclosporine)
  • Seroquel (quetiapine)
  • Some statins, such as Zocor (simvastatin) and Lipitor (atorvastatin)

Grapefruit may also interact with certain herbal medicines. Discuss your complete medication list and any supplements you take with your healthcare provider or pharmacist before adding a grapefruit-based supplement to your regimen.

When you pick up a prescription medication from the pharmacy, read the patient information sheet or product label to see if your drug is affected by grapefruit. Ask the pharmacist if you're unsure.

Frequently Asked Questions

  • Is grapefruit seed extract the same as grapefruit seed oil?

    No. Grapefruit seed extract is a liquid made from the seeds, pulp, and membranes of a grapefruit. The oil is expressed from the rind of the grapefruit and is intended for use in oils, soaps, or cosmetics. The oil is typically used on the skin or as aromatherapy and is not intended to be ingested.

  • Does grapefruit seed extract help treat candida?

    GFSE has been promoted to fight Candida, a fungal infection that mostly occurs in and around the mouth (thrush).

    While GFSE has long been thought to have antifungal and antimicrobial properties, no human research supports its use for treating thrush. Nutritional supplements are also not intended to treat any disease or infection.

    Your best bet is to consult with a healthcare provider about evidence-based treatments for the infection.

Sources of Grapefruit Seed Extract & What to Look For

Grapefruit seed extract supplements are available as liquid concentrates, tablets, and capsules. GFSE has also been formulated in mouthwashes, drops, and other personal care products.

Some supplements contain GFSE, but others may have a mixture of extracts. It is important to read the supplement's facts and ingredients label.

That being said, some GFSE supplements have been found to be adulterated with chemicals, such as benzethonium chloride and triclosan. These chemicals are found antibacterial soaps and cleansers and could be harmful if ingested in high doses.

Dietary supplements are not regulated like prescription medications in the United States. Therefore, some may be safer than others. When choosing a supplement, consider factors such as third-party testing, potential drug interactions, and other safety concerns. Talk to a healthcare provider or a registered dietitian nutritionist (RD or RDN) about supplement quality and safety.

Summary

Grapefruit seed extract supplements are marketed for numerous conditions, but their ability to provide any sort of benefit remains uncertain. GFSE products also carry risks of interactions with medications and potential contamination. Given this, plus the lack of any supporting research, the risks of taking these supplements likely outweigh the supposed benefits.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Gafner S, Blumenthal M, Foster S, Cardellina JH 2nd, Khan IA, Upton R. Botanical ingredient forensics: detection of attempts to deceive commonly used analytical methods for authenticating herbal dietary and food ingredients and supplements. J Nat Prod. 2023;86(2):460-472. doi:10.1021/acs.jnatprod.2c00929

  2. Heggers JP, Cottingham J, Gusman J, et al. The effectiveness of processed grapefruit-seed extract as an antibacterial agent: II. Mechanism of action and in vitro toxicity [published correction appears in J Altern Complement Med 2002;8(4):521. Reagor Lana [corrected to Reagor Lee]]. J Altern Complement Med. 2002;8(3):333-340. doi:10.1089/10755530260128023

  3. von Woedtke T, Schlüter B, Pflegel P, Lindequist U, Jülich WD. Aspects of the antimicrobial efficacy of grapefruit seed extract and its relation to preservative substances contained. Pharmazie. 1999;54(6):452-456.

  4. Grapefruit and drug interactions. Prescrire Int. 2012;21(133):294-298.

  5. Food and Drug Administration. Grapefruit juice and some drugs don't mix.

  6. Seden K, Dickinson L, Khoo S, Back D. Grapefruit-drug interactionsDrugs. 2010;70(18):2373-2407. doi:10.2165/11585250-000000000-00000

  7. Roy S, Zhang W, Biswas D, Ramakrishnan R, Rhim JW. Grapefruit seed extract-added functional films and coating for active packaging applications: a review. Molecules. 2023;28(2):730. doi:10.3390/molecules28020730

Bio headshot for Jennifer Lefton

By Jennifer Lefton, MS, RD/N, CNSC, FAND
Lefton is a registered dietitian/nutritionist and certified nutrition support clinician with over 20 years of experience in clinical nutrition.