Although cornstarch is a common ingredient used in cooking, eating cornstarch can give some people abdominal pain or cause an intestinal blockage, states MedlinePlus. It's unlikely that ingesting cooking cornstarch will cause long-term or serious problems, but ingesting starch used for laundry can be very dangerous.
Cooking starch is generally used as a thickener in sauces and gravies, and eating cornstarch in this form generally causes no problems. Some people suffering from a disorder known as pica crave the sensation of eating starch or other powdery substances. These individuals might eat enough starch to harm their digestive systems. Eaten in large quantities, cornstarch can cause discomfort or even a blockage, according to MedlinePlus. If a person is in pain, cannot drink liquids or experiences other severe symptoms, it is recommended that they seek medical treatment immediately.
Cornstarch contains trace amounts of corn protein, so people with corn allergies may experience allergic reactions, including anaphylaxis, states About.com. Cornstarch may be used to coat the inside of plastic food wrappers or paper food packaging; individuals with severe corn allergies must be aware of all potential sources.
Laundry starch, which is another form of cornstarch, is used to stiffen clothing. Eating laundry starch can be highly dangerous and should be treated as a poisoning incident, explains MedlinePlus. Side effects of eating laundry starch include jaundice, diarrhea, vomiting, convulsions, blisters, fever and coma.