There are two types of bedding that you need to provide for your hamster. These are the floor covering and nesting material. Wood shavings are normally used for floor covering but there are a few different types available from pets stores, not all of which are safe for your hamster.
Nesting material is softer and can also be bought from pet stores, or alternatively it can be made more cheaply at home. However, as with floor covering, it is important that you only use nesting material that is safe for your hamster.
Floor covering is needed to provide a comfortable surface for your hamster to live on, and to soak up urine and any other moisture. Wood shavings are most commonly used, but to ensure they are safe they should be from hard woods such as aspen as these are generally chemical-free. You can also use small animal litter made from wood pulp.
Nesting material is used by your hamster for making a bed and for burrowing in. Anything used as nesting material should break easily and dissolve in water. This ensures that your hamster cannot get caught in it or become ill from eating any. Soft shredded paper bedding is therefore a suitable option, and can be made by tearing up toilet paper or paper towel into strips to avoid the cost of buying commercial bedding. Make sure, however, that the paper used is not dyed or scented.
Alternatively, it is safe to use hay as long as it is not moldy or dusty. But hay can become infested with mites and should therefore be removed if your hamster gets a mite infestation.
Certain items are harmful and so should never be used as bedding for your hamster.
Pine and cedar wood shavings can cause respiratory infections so should not be used as floor covering, although pine can be safer if it is kiln dried. Scented wood shavings are also unsafe, while corn cob bedding should be avoided as it can sometimes start to mold and can swell in the stomach if eaten. Sawdust is unsuitable as it can cause irritation to your hamster's eyes.
For nesting material, any fluffy types of bedding should be avoided as they can become stuck in cheek pouches and your hamster can potentially get caught in the fibers. Furthermore, wool and pieces of material do not dissolve easily and can cause blockages if eaten. Straw is unsuitable as well since its sharp edges can cause injury.