- Almonds — contain cyanide, which can kill hamsters in enough quantity
- Celery, whole stalks — stringy texture could choke a hamster
- Chocolate (particularly dark chocolate) — contains theobromine, which causes circulatory problems for hamsters
- Fruits, unwashed — poses danger to your hamster from pesticides
- Garlic — may cause indigestion
- Kidney beans, uncooked —toxic to hamsters
- Lettuce, iceberg — can cause liver problems in hamsters if eaten in excess (more than a few small pieces every three days)
- Onion — N-propyldisulfide causes damage to the hamster’s red blood cells
- Peanuts — contain aflatoxin, which is toxic to hamsters in too large a quantity
- Potato, Potato tops — toxic to hamsters
- Rhubarb, Rhubarb leaves —toxic to hamsters
- Spicy or seasoned products — may cause indigestion in hamsters
- Sugary products — bad for hamsters’ teeth and are fattening
- Tomato leaves — toxic to hamsters
- Vegetables, unwashed — poses danger to your hamster from pesticides
Sources from http://www.smallanimalchannel.com/hamsters/hamster-diet/what-hamsters-should-not-eat.aspx