ROCKFORD, Ill. (WTVO) — If you’re eyeing that week-old pizza in the fridge and wondering if it’s safe to eat it, you might want to think twice.

According to the USDA, if the pizza has been refrigerated at a temperature below 40 degrees, its only safe to eat for up to 4 days.

The USDA says that after 4 days, you run the risk of getting a food-borne illness, such as Salmonella, norovirus, or other diseases with horrifying Latin names.

That’s assuming that you followed the “2-hour rule” beforehand, which means the pizza was refrigerated and not left at room temperature for longer than 2 hours.

Bacteria grows rapidly on foods such as meat, poultry, eggs, and casseroles that have been left at room temperature (between 40 and 140 degrees) for longer than 2 hours. Beyond that, the number of bacteria can double every 20 minutes in what is called the “danger zone” temperatures.

If the food has been left in temperatures above 90 degrees, it must be refrigerated in less than 1 hour, the USDA says.

Cooked pizza stored in a freezer can stay safe for between 1 and 2 months.

“When in doubt, throw it out!” is the USDA’s motto.