Drugs A - Z
Onion (Allium cepa)
Generic Name: Allium
CategoryHerbs & Supplements
Allium cepa, Allium cepa L., allium vegetables, botanicals, Liliaceae (family), onion extract, onion juice, pickling onions, white onion.
Onion (Allium cepa L.) is a widely used around the world as a food product and has also been used for medicinal applications.
As onion is a commonly consumed food, it is considered likely safe in smaller amounts, although there are reports of skin rash and gastrointestinal problems in sensitive individuals.
EvidenceDISCLAIMER: These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Early study suggests that application of an alcoholic onion extract on the skin may reduce allergic responses, such as wheals ("hives") and flares. More research is needed in this area.
Alopecia areata (hair loss):
Study using topical onion juice increased hair regrowth in alopecia areata (hair loss) patients, especially women. More research is needed in this area to confirm these results.
One clinical trial found that fresh onion significantly decreased serum glucose (blood sugar) levels in diabetics. More research is needed in this area to confirm these results.
Scar prevention :
Several trials have been conducted using combination products that include an onion extract. These studies have investigated onion's potential role in scar healing in adults and children, specifically due to injuries from laser tattoo removal or surgery. The overall results are mixed, and more research is needed to make a strong recommendation.
TraditionWARNING: DISCLAIMER: The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Antibacterial, antifungal, antimicrobial, antioxidant, antiplatelet (blood thinning), arthritis, asthma, atherosclerosis (hardening of the arteries), cancer, cardiovascular (heart) disease, cataract, chilblains (inflammation of the hands and feet caused by exposure to cold and moisture), coronary heart disease, gastrointestinal disorders, hypercholesterolemia (high cholesterol), insecticidal, lung cancer, obesity, osteoporosis, prebiotic, splinters, stomach cancer, thrombosis (blood clot).
Adults (over 18 years old)
There is no proven effective medicinal dose of onion in adults. However, Mederma® (Merz Pharmaceuticals, Greensboro, NC, USA) has been applied to the skin three times daily for eight weeks. A topical onion gel extract applied three times a day for one month has also been used.
Children (under 18 years old)
There is no proven safe or effective medicinal dose of onion in children.
SafetyDISCLAIMER: Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.
Avoid in individuals with a known allergy or hypersensitivity to onion (Allium cepa) or its constituents. In some individuals, handling onion bulbs has caused skin rash, painful tingling in the fingers, or a reddening of the skin.
Side Effects and Warnings
Onion is likely safe when consumed in food amounts and when onion extract applied to the skin for scar healing.
Onion should be used cautiously in patients with hematologic (blood) disorders or taking anticoagulants or antiplatelets (blood thinners), in patients with diabetes or hypoglycemia (high or low blood sugar), and in patients with hypotension (low blood pressure).
The primary adverse effects associated with onion are dermatologic (pemphigus, a chronic blistering disease, and skin rash) and gastrointestinal (heartburn, dyspepsia (upset stomach), gastric acidity, and gastroesophageal reflux).
In clinical studies, onion has been found to lower blood pressure in both patients with and without hypertension (high blood pressure).
Avoid in patients who are allergic or hypersensitive to onion or plants in the Lilaceae family.
Pregnancy & Breastfeeding
Onion, in medicinal amounts, is not recommended in pregnant or breastfeeding women due to a lack of available scientific evidence.
Interactions with Drugs
Meals including onion have induced heartburn, dyspepsia (upset stomach), gastric acidity, and gastroesophageal reflux in clinical trials. Use onion cautiously with antacids.
Allium plants, such as onion, may have antibiotic effects, and may have additive effects when used with other antibiotics.
Onion may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs (NSAIDS) such as inbuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
Onion may lower blood sugar. Caution is advised in patients with diabetes (high blood sugar) or hypoglycemia (low blood sugar), and in those taking drugs that affect blood sugar. Serum glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
Onion and onion essential oil may prevent fat-induced increases in serum cholesterol. Use cautiously with cholesterol-lowering medications.
Onion or onion extract may have anticancer effects. Use cautiously when taken with medications to prevent or treat cancer.
Onion may lower blood pressure; use cautiously with blood pressure medications.
Onion may inhibit bone resorption; use cautiously with osteoporosis agents.
Interactions with Herbs & Dietary Supplements
Allium plants, such as onion, may have antibiotic effects, and may have additive effects when used with other antibiotic herbs.
Onion may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto.
Onion may lower blood sugar. Caution is advised in patients with diabetes or hypoglycemia, and in those taking herbs or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and doses may need adjustment.
Onion or onion extract may have anticancer effects. Use cautiously with herbs and supplements taken to prevent or treat cancer.
Onion and onion essential oil may prevent fat-induced increases in serum cholesterol; use cautiously with herbs and supplements taken for cholesterol.
Onion may decrease systolic and diastolic blood pressure; use cautiously if taking herbs or supplements for blood pressure.
Onion may inhibit bone resorption; use cautiously with herbs or supplements taken for osteoporosis.
This information is based on a systematic review of scientific literature, and was peer-reviewed and edited by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): J. Kathryn Bryan (Natural Standard Research Collaboration); Nicole Giese, MS (Natural Standard Research Collaboration); Julie Goodfriend, PharmD (Northeastern University); Tera Stock, PharmD (Massachusetts College of Pharmacy and Health Sciences); Shaina Tanguay-Colucci, BS (Natural Standard Research Collaboration); Catherine Ulbricht, PharmD (Massachusetts General Hospital); Wendy Weissner, BA (Natural Standard Research Collaboration).
BibliographyDISCLAIMER: Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.
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Chung VQ, Kelley L, Marra D, et al. Onion extract gel versus petrolatum emollient on new surgical scars: prospective double-blinded study. Dermatol Surg 2006;32(2):193-197.
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Heber, D. Vegetables, fruits and phytoestrogens in the prevention of diseases. J Postgrad.Med 2004;50(2):145-149.
Ho WS, Ying SY, Chan PC, et al. Use of onion extract, heparin, allantoin gel in prevention of scarring in chinese patients having laser removal of tattoos: a prospective randomized controlled trial. Dermatol Surg 2006;32(7):891-896.
Hubbard GP, Wolffram S, de Vos R, et al. Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: a pilot study. Br J Nutr 2006;96(3):482-488.
Lanzotti V. The analysis of onion and garlic. J Chromatogr A 4-21-2006;1112(1-2):3-22.
Rose P, Whiteman M, Moore PK, et al. Bioactive S-alk(en)yl cysteine sulfoxide metabolites in the genus Allium: the chemistry of potential therapeutic agents. Nat Prod Rep. 2005;22(3):351-368.
Schulz M, Lahmann PH, Boeing H, et al. Fruit and vegetable consumption and risk of epithelial ovarian cancer: the European Prospective Investigation into Cancer and Nutrition. Cancer Epidemiol.Biomarkers Prev. 2005;14(11 Pt 1):2531-2535.
Sengupta A, Ghosh S, Bhattacharjee S. Allium vegetables in cancer prevention: an overview. Asian Pac.J Cancer Prev. 2004;5(3):237-245.
Srinivasan K. Plant foods in the management of diabetes mellitus: spices as beneficial antidiabetic food adjuncts. Int J Food Sci Nutr 2005;56(6):399-414.
Wetli HA, Brenneisen R, Tschudi I, et al. A gamma-glutamyl peptide isolated from onion (Allium cepa L.) by bioassay-guided fractionation inhibits resorption activity of osteoclasts. J Agric Food Chem 5-4-2005;53(9):3408-3414.
Zurada JM, Kriegel D, Davis IC. Topical treatments for hypertrophic scars. J Am Acad Dermatol 2006;55(6):1024-1031.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.