Lactaid "Fast Act," like its predecessor, Lactaid "Ultra," is the only kind anyone with digestive problems should use.
Regular or "Original" Lactaid is bound with Mannitol, which is a laxative. As a result, anyone who's got to take more than one or two should NOT use this product.
Unfortunately, only the "Original" Lactaid comes in a bottle of pills. Lactaid "Fast Act" comes only in a paper-foil sheet, with each pill individually wrapped, which makes using any substantial number of pills a huge pain in the neck.
As a result, your choices are take a product that may make you sick, or waste your time tearing the packaging for each pill.