Many food-safety resources, including the USDA, recommend against consuming unbaked cookie dough because of the risk of illness. Eating raw cookie dough can result in gastrointestinal illness that may even lead to hospitalization in extreme cases. However, the potential illnesses are not generally caused by intestinal parasites such as worms, which are far more common in meats. Rather, when raw cookie dough causes illness, it's generally because it has been contaminated with harmful bacteria.
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Carriers of Parasites
Though parasites that can cause intestinal infections are sometimes found in fresh fruits and vegetables, these parasites are most frequently contracted by ingesting raw or undercooked seafood or pork products. As cookie dough rarely contains ingredients that commonly carry parasites, this issue is not health experts' primary concern when it comes to the ingestion of raw cookie dough.
Cookie dough does usually contain raw eggs, which have been identified as a common carrier of Salmonella bacteria. Salmonella bacteria can cause an infection of the small intestine's lining called salmonellosis. For this reason, you should avoid eating raw cookie dough or any other product that contains raw or undercooked eggs. It's also important to wash your hands frequently when cooking with raw eggs to ensure that no other foods are contaminated by the bacteria.
Salmonellosis is a potentially serious illness, particularly in young children, the elderly and those with compromised immune systems. It causes symptoms such as abdominal cramps, vomiting, diarrhea, fever and chills. The infection can last two to five days and, in extreme cases, those affected may require hospitalization for dehydration. Though salmonellosis usually clears up on its own and has few long-term complications, the bacteria also can cause meningitis and septicemia in rare cases.
The USDA recommends that you avoid eating raw cookie dough. If the dough is contaminated with bacteria, exposing the dough to heat while baking it kills the bacteria that can make you sick. To reduce the risk of encountering eggs containing Salmonella bacteria, you should purchase pasteurized eggs and egg products for baking. Never leave raw cookie dough out at room temperature; rather, refrigerate the remaining dough while the first batch is baking.