The name "bitter orange", also known as Seville orange, sour orange, bigarade orange, and marmalade orange, refers to a citrus tree (Citrus × aurantium) and its fruit. Many varieties of bitter orange are used for their essential oil, which is used in perfume and as a flavoring.

Citrus aurantium L, the FDA received 22 adverse event reports (AERs) involving products that were reported to contain Citrusaurantium (bitter orange) extract (BOE). During this same time, 10 clinical cases reports were published involving adverse events associated with products that contained BOE (C. aurantium) or its predominant alkaloid p-synephrine.

Extracts of Citrus aurantium L. (Rutaceae) unripe fruits have gained popularity for the treatment of obesity. Due to the wide use of C. aurantium/p-synephrine-containing products, this research was undertaken to evaluate its subchronic toxicity in mice and their actions in oxidative stress biomarkers.