Rosemary essential oil may have epileptogenic (can cuae epileptic seizures) properties, as a handful of case reports over the past century have linked its use with seizures in otherwise healthy adults or children.
Rosemary essential oil is potentially toxic if ingested. Large quantities of rosemary leaves can cause adverse reactions, such as coma, spasm, vomiting, and pulmonary edema (fluid in the lungs) that can be fatal. Avoid consuming large quantities of rosemary if pregnant or breastfeeding.
Rosemary contains a number of potentially biologically active compounds, including antioxidants such as carnosic acid and rosmarinic acid. Other bioactive compounds include caffeic acid, ursolic acid, betulinic acid, rosmaridiphenol, and rosmanol.
Rosemary may also be useful in the prevention and treatment of headlice