There’s many different kinds of beddings and litters. Some are great to use, while others are extremely harmful to your rats.

Never use:
Cedar or Pine beddings–These are extremely toxic to your rats. Their heavy aroma masks the urine smell, but if rats breathe in these fumes over long periods of time can compromise their immune systems and put them at a high risk of respiratory problems, such as mycoplasma.
Clay litters–Dusty dusty dusty! Even if it says that it’’s 99.9% dust free, it’s still way too dusty for rats.
Corn Cob–When corn cob bedding gets wet, it tends to grow mold and rot causing odors and an increase of bacteria. If you use corn cob, change it very often.

Safe to use:
CareFRESH–Great for dig boxes. Does not keep odor down for very and will need to be chanced frequently. It is expensive for how often it needs to be chanced.
Yesterdays News–Recycled newspaper pellets. Very absorbent and keeps odor down. Fairly priced and easy to find.
Cell Sord Plus–Recycled newspaper pellets. Excellent odor control.
Critter Country–Claims that it is the best odor controlling litter. Dust-free and safe if ingested.
Shredded Paper–Needs to be changed often because it gets mushy when wet. If using newspaper, be sure that it is printed with non-toxic soy or vegetable ink. Light colored rats will appear dirty because of the ink.
Cloth–A good alternative to the other beddings if you or your rat have allergies. Use cloth that doesn’t unravel easily (old t-shirts and fabric diapers) because it could get tangled around their arms, legs, and tail and cause injury. Change every day to every other day.