Sulphite, also spelled as sulfite, are compounds that contain the sulfite ion. Sulfites are substances that naturally occur in some foods and the human body. Sulphites are used as food preservatives. Sulfites occur naturally in all wines to some extent. Sulfites are commonly introduced to arrest fermentation at a desired time, and may also be added to wine as preservatives to prevent spoilage and oxidation at several stages of the winemaking. Sulfites are often used as preservatives in dried fruits, preserved radish, and dried potato products. Sulfites are counted among the top nine food allergens, but a reaction to sulfite is not a true allergy. It may cause breathing difficulty within minutes after eating a food containing it. Asthmatics and possibly people with salicylate sensitivity (or aspirin sensitivity) are at an elevated risk for reaction to sulfites. Other potential symptoms include sneezing, swelling of the throat, hives, and migraine.