Onion
Cepa
- Known today as
- Allium cepa.
- Kind
- Plant, in 1 older authority
- Constituents
- allyl propyl disulfide, syn-propanethial-S-oxide, quercetin, and 1 more
- Earliest authority here
- Herodotus (c. 484–c. 425 BC)
- Qualities
- Hot and dry (Galenic tradition). What the degrees mean
- In other databases
- Plants of the World Online search · GBIF search · Wikidata search
Onion: what was it used for?
To ripen boils, provoke urine, and draw the menses; roasted for earache.
Onion: what does modern science say?
Nutritious; no strong medicinal evidence.
Pharmacognosy & Toxicology
- Constituents
- allyl propyl disulfide ChEMBL
- syn-propanethial-S-oxidethe lachrymatory factor
- quercetin ChEMBLup to 50 mg per 100 g in red onions
- fructans
- Mechanism
- The sulfur compounds inhibit platelet aggregation and are antibacterial; the roasted onion in the ear was a warm poultice; onion extract gel for scars (Mederma) has failed in controlled trials. Onion is toxic to dogs and cats by oxidising their haemoglobin, not to people.
- Toxic dose
- A food.
- Standing
- A food; the German Commission E lists it for appetite and against atherosclerosis on tradition.
- Blumenthal, M., ed. (1998). The Complete German Commission E Monographs, “Onion.” Standard reference work
- Chung, V. Q., et al. (2006). “Onion extract gel versus petrolatum emollient on new surgical scars.” Dermatologic Surgery 32. Verified against its record · doi:10.1111/j.1524-4725.2006.32045.x
The abstract of each source, beneath its citation. For Club members. About the Club or sign in.
Constituent names open the compound’s record at PubChem, and “ChEMBL” beside a name opens its record at ChEMBL, the European Bioinformatics Institute’s database of bioactive molecules. Where a mechanism line was checked against ChEMBL (ChEMBL 37, read 1 October 2026), the check is shown with the measured value and its source paper, or says plainly that nothing has been measured. Doses are as the references give them, for description only; this is not medical advice. Each source carries the result of its check against Crossref, PubMed, or the authority’s page: see Verification.
Onion: what lore surrounds it?
A widespread modern folk belief holds that a cut onion left in a sickroom, or under the bed or against the feet overnight, draws illness out of the body or the air. It has been traced and debunked repeatedly, and rests on nothing beyond the older, equally unproven idea that onions purify foul air: a living piece of folklore, not a remedy.
Onion: what did the older authorities say?
- Herodotus
- The inscription he reports on the Great Pyramid counted the onions, radishes, and garlic eaten by the workmen.
Sources
- Herodotus, Histories II. Verified against its record · doi:10.1093/oseo/instance.00271233
- Snopes, “Do Onions Fight Off the Flu Virus?” Book, seen in reviews
Verification
- Checked
- October 1, 2026
- Passes
- Every sentence read against its sources, in the pass over the remaining 343 entries
- The Standing line checked against the authority it names (EMA, WHO, FDA, CITES, Commission E)
- Every dated or regulatory claim checked by category across the database
- Sources
- 4 cited: 2 verified against its record, 1 standard reference work, 1 book, seen in reviews. 1 with the abstract on file.
- Corrections
- None were needed.
What was checked, how, and what was found is set out on the Verification page. A checked source is one whose record was found; it does not make the entry medical advice.
Cite This Entry
Version 1 · first published September 25, 2026
- Chicago
“Onion.” In Materia Medica, edited by B. C. P. Statema. Version 1. The Thinking Press, 2026–. Last modified September 25, 2026. https://thethinkingpress.org/materia-medica/onion.
- MLA
“Onion.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 25 Sept. 2026, thethinkingpress.org/materia-medica/onion. Accessed 8 Oct. 2026.
- APA
Onion. (2026, September 25). In B. C. P. Statema (Ed.), Materia medica (Version 1). The Thinking Press. Retrieved October 8, 2026, from https://thethinkingpress.org/materia-medica/onion
Club members keep entries on a shelf with private notes, print the plates as cards, and receive an entry by email each week. Create a free account before January 1, 2027 and all of it is yours for good. About the Club
See Also
Sharing quercetin
Also in Herodotus
Radish in Herodotus · Myrrh in Herodotus · Storax calamite in Herodotus · Labdanum in Herodotus · everything Herodotus names →
Drawing on the same sources: Herodotus, Snopes, Blumenthal, Chung
Alum · Hemp · Garlic · Jack-o’-lantern · Sarsaparilla · Masterwort and angelica · Turpentine · Cochineal · the bibliography →
Of the same qualities: hot and dry
Parsley · Rosemary · Long pepper · Rue · Lavender · what the degrees mean →
Nearby in the alphabet
Onycha and stacte (Ingredients of the Temple incense (Exodus 30) · Olive-wood ash lye (Lye made by steeping the ash of olive wood in river water) · Opium poppy (Papaver somniferum) · Olive oil and holy water (Fine olive oil) · Opopanax (a Mediterranean plant of the carrot family) · Oil of the sick · Orache (garden orache, a spinach-like plant) · Oil of catechumens
Historical description, not medical advice.