Different cleaners work for different types and severity of clogs — for example, one that works for a slow-flowing drain will probably not work for a complete blockage. Here are two types of cleaner to look for while shopping:
Enzymatic cleaners are slower to clear clogs but are usually less harmful to your plumbing (or yourself). The enzymes (bacteria) in the cleaner slowly break down organic soils such as hair and food that can be found in your drain but might not be strong enough to dissolve a complete blockage.
Chemical-based drain cleaners work the fastest, but also have the potential to cause more damage. Depending on the type of pipes you have in your home, damage can occur when using chemicals. PVC pipes can warp or soften from heat generated by chemical use. For metal pipes, excessive use can cause pipes to corrode and in extreme cases cause holes to develop.