Substrates commonly used in reptile enclosures include those in the list below. Some of these substrates are inappropriate for some reptiles. Some are inappropriate for all reptiles and are included here so that you will be forewarned against buying them despite pet store recommendations and the implied or explicit wording on product packaging and advertisements. Substrates should not be collected in the wild as the soil, leaves, sand, gravel, etc., may contain organisms that are harmful to your reptile. Even if you don't use herbicides and pesticides in your yard, these chemicals are transported through the air as both dry and wet deposits, and so contaminate soil, leaves, and the woody parts of plants, even those at some distance from the point of application.
Particles become stuck to the tongue and are swallowed.
Over time, they may build up in the gut causing a serious, even fatal, impaction. Particulate substrates can be problematic for both snakes and lizards as it can become stuck to their hemipenes or everted cloacal tissues when they are defecating, being taken up into the cloaca when the tissue or hemipenes are retracted. Some fine particulates may get into the eyes of lizards who have no moveable eyelids, causing irritation, injury, serious infection, or even blinding them. Small, sharp particulates may also scratch the protective covering of snake's eyes, which in turn may lead to infection. Sometimes, the most convenient substrate is not the best substrate for the reptile.