Arachis oil

Cross-reactivity

Case notes

Most label scanning happens fast, and the word "peanut" is what eyes are trained to catch. "Arachis" slips past because it reads like a botanical curiosity rather than a warning. It is the botanical name for peanut, and it shows up most often in cosmetics and some medications — places parents may not think to scan as carefully as a snack wrapper. The same ingredient also travels under Peanut oil, Groundnut oil, and Arachis hypogaea oil, so a single product can list it in a form you recognize while another lists it in a form you don't.

The proteins behind the concern are storage proteins: Arachis oil sits in the Legumins (11S Globulins) family, which includes Legumin (Ara h 3), and the Vicilins (7S Globulins) family, which includes Vicilin (Ara h 1). Ara h 1 is described as remaining stable during processing and able to persist in refined products, which is one reason an oil-form ingredient still deserves a second look rather than an assumption. Reactions in these families are generally characterized as moderate to severe, with anaphylaxis noted for the vicilin group.

There is also a legume overlap worth knowing when you compare labels. Ara h 1 shares structural homology with soy vicilin (Gly m 5), and Ara h 3 with soy legumin (Gly m 6); roughly 5 to 10 percent of people allergic to peanut react to soy. That does not mean soy and peanut are interchangeable on a label — it means the two often appear near each other in ingredient lists, and both are worth reading in full.