Health Canada is reminding Canadians of the importance of properly cooking fresh fiddleheads before eating them. Fiddleheads are the curled, edible shoots of the ostrich fern. They are collected along the banks of rivers and streams and sold as a seasonal vegetable at farmer’s markets, roadside stands and in some grocery stores. There have been cases of temporary illness in Canada and the United States associated with eating raw or undercooked fiddleheads. Studies to date have not determined the cause of these illnesses. Symptoms of illness usually begin 30 minutes to 12 hours after eating raw or undercooked fiddleheads and may include diarrhea, nausea, vomiting, abdominal cramps and headaches. Illness generally lasts less than 24 hours but can result in dehydration, particularly among the elderly and in infants. There have been no reported cases of illness associated with eating fully cooked fiddleheads.