Food Safety Report: Portillo's Downers Grove, Butterfield Road, Downers Grove, IL, USA 2 years ago • details 24 Comments Comment Suspected food poisoning. Symptoms: Diarrhea, Nausea, Vomiting, Stomach Pain Suspected source: French fries and chicken strips Onset: Less than 4 hours Duration: 4 to 12 hours Sick: 3 people