Onion (Allium cepa)
Synopsis of onion
Onion (Allium cepa) is a widely consumed culinary vegetable and medicinal plant known for its pungent flavor, aromatic compounds, and impressive pharmacological profile. Rich in sulfur-containing compounds—especially allicin, quercetin, and cysteine sulfoxides—onion exhibits potent antioxidant, anti-inflammatory, antimicrobial, and cardioprotective effects. It also contains flavonoids, phenolic acids, and organosulfur compounds that contribute to its wide-ranging health benefits.
In herbal medicine, onions are used to support respiratory health, regulate blood sugar, enhance circulation, and reduce inflammation. They are known for their expectorant qualities, helping to break up mucus in the lungs during colds and coughs. Onion’s quercetin content is a natural antihistamine, supporting allergy relief and reducing oxidative stress. The sulfur compounds promote cardiovascular health by lowering blood pressure and cholesterol while inhibiting platelet aggregation.
Raw onions have mild antibacterial properties and have been used topically for minor wounds, insect bites, and fungal infections. Onion extract is sometimes used in scar-reducing ointments. Nutritionally, onions are low in calories but high in vitamin C, B vitamins, and minerals like chromium and potassium.
Historical Use in Medicine
Onion has been revered as both food and medicine since ancient times. In ancient Egypt, onions were considered sacred and were placed in the tombs of pharaohs; they believed the concentric layers symbolized eternal life. Egyptian laborers consumed onions regularly to enhance strength and endurance, a tradition that may reflect its adaptogenic and circulatory benefits.
Greek physician Hippocrates used onions for wound healing and to treat pneumonia and diuretic imbalances. Roman soldiers ate onions for strength and treated joint pain and wounds with onion poultices. In Traditional Chinese Medicine, onions were believed to warm the lungs, invigorate circulation, and disperse cold—making them a common remedy for colds, coughs, and bronchial congestion.
In Ayurvedic medicine, onions were seen as both nourishing and detoxifying. They were often cooked into tonics or poultices for digestive upset, joint pain, or fever. Red onions were thought to strengthen the reproductive system and act as an aphrodisiac, while raw onions were chewed to prevent infections or applied to bites and stings.
Throughout the Middle Ages and into early modern Europe, onions were among the few plants valued for both their culinary and healing properties. Folk remedies included wearing onions to prevent the plague, placing sliced onions around a room to “absorb sickness,” and using onion syrup to treat persistent coughs and sore throats.
Today, onions continue to be a cornerstone in both traditional and functional medicine, combining culinary value with therapeutic versatility.
Onion is used for these health conditions
Appetite (deficient) (Traditional)
Arteriosclerosis (Scientific)
Asthma (Traditional)
Blood Clots (prevention of) (Scientific)
Blood Poisoning (Traditional)
Bronchitis (Traditional)
Bruises (healing) (Traditional)
Burns and Scalds (Traditional)
Cancer (natural therapy for) (Scientific)
Cancer (prevention) (Scientific)
Cardiovascular Disease (Scientific)
Cholesterol (high) (Scientific)
Circulation (poor) (Traditional)
Colds (general) (Traditional)
Colds (prevention) (Traditional)
Congestion (bronchial) (Traditional)
Congestion (lungs) (Traditional)
Congestion (sinus) (Traditional)
Constipation (adults) (Traditional)
Cough (dry) (Traditional)
Cough (general) (Traditional)
Cough (spastic) (Traditional)
Cuts (Traditional)
Diabetes (Scientific)
Digestion (poor) (Traditional)
Ear Infection or Earache (Traditional)
Edema (Traditional)
Fever (Traditional)
Gall Stones (Traditional)
Gingivitis (Traditional)
Glands (swollen lymph) (Traditional)
Hair (loss or thinning) (Traditional)
Headache (general) (Traditional)
Headache (sinus) (Traditional)
onion is used to support these body systems
Arteries (Scientific)
Blood (Traditional)
Capillaries (Scientific)
Circulatory System (Scientific)
Digestive System (Scientific)
Gastrointestinal Tract (Scientific)
Glandular System (Traditional)
Heart (Scientific)
Immune System (Scientific)
Intestinal System (Scientific)
Liver (Traditional)
Lungs (Traditional)
Lymphatics (Traditional)
Mucus Membranes (Traditional)
Respiratory System (Traditional)
Sinuses (Traditional)
Spleen (Traditional)
Stomach (Traditional)
