Cats should not eat oranges. Oranges contain strong acidic components that can irritate a cat's stomach and intestines. Eating too many oranges can lead to poisoning, and even cause persistent diarrhea and vomiting. Oranges also contain essential oils, which have a strong odor and can irritate a cat's respiratory tract, causing sneezing. Other possible symptoms include itchy eyes and nose, runny nose, facial swelling, difficulty breathing, and itchy skin. 
Foods that cats cannot eat:
1. Cats should not eat scallions, onions, or leeks, as these contain components that damage cats' red blood cells, causing symptoms such as anemia, diarrhea, hematuria, vomiting, and fever. In the most severe cases, they can cause death in cats.
2. Avocado. Avocados contain a chemical toxin that is very harmful to cats, causing digestive problems, breathing difficulties, high fever, and in large quantities, death.
3. Raw potatoes. Raw potatoes contain a toxic substance called nicotine, which can cause severe gastrointestinal upset in cats. Furthermore, sprouted potatoes, whether cooked or not, can lead to heart problems in cats.
