Will mashed potatoes make you sick after 4 days?

It's highly likely that mashed potatoes left out at room temperature for 4 days will make you sick. Here's why:

* Bacteria Growth: Mashed potatoes, like most cooked foods, provide a perfect breeding ground for bacteria like Salmonella, E. coli, and Staphylococcus aureus. These bacteria multiply rapidly at room temperature, producing toxins that can cause food poisoning.

* Spoilage: Even if no visible mold or other signs of spoilage are present, the potatoes will have likely begun to decompose, making them unsafe to eat.

General Food Safety Rule: The "danger zone" for bacterial growth is between 40°F (4°C) and 140°F (60°C). Foods left out at room temperature for longer than 2 hours (or 1 hour in temperatures above 90°F) should be discarded.

Exceptions:

* Refrigeration: If the mashed potatoes were properly refrigerated (below 40°F) within 2 hours of being made, they might be safe for a few days, but it's still best to consume them within 3-4 days for optimal freshness and safety.

* Freezing: Freezing can help extend the shelf life of mashed potatoes. Properly frozen mashed potatoes can last for several months.

Symptoms of Food Poisoning: Symptoms of food poisoning can include nausea, vomiting, diarrhea, stomach cramps, and fever. If you experience these symptoms after eating mashed potatoes, it's important to see a doctor.

Always err on the side of caution when it comes to food safety. If in doubt, throw it out!