A hairball is a solid mass of cat hair that forms in a cat's stomach or intestines over time as the result of their daily grooming habits. If large enough, they can cause an intestinal blockage. Most cats are susceptible to hairball problems due to the compulsive, and sometimes excessive, grooming. Long-haired cats tend to have even more problems due to their thicker coats.
Simply speaking, hairballs are a digestive problem, and a cat's hair is basically just dead protein. This is where digestive enzymes come into the picture. Their function, basically, is to break down protein; therefore, a digestive enzyme supplement should help your cat to effectively digest the hairball instead of having to cough the darn thing up, which is much less drama for your cat and must less mess for you to clean up!
Also, enzymes provide a better solution to your cat's problem hairballs because they are a natural product already used in the body. Further, they do not result in the side-effects common in other hairball treatments and remedies such as laxatives and pastes.
The most difficult part of giving your cat digestive enzymes may just be getting them to eat it, which was my problem with all three cats. So, what I do is just crush them into a powder, then sprinkle it over their dry food. If you feed your cat wet food, it should be even easier to just mix it into their food.
Another way to help your cat is brushing. I have noticed a remarkable improvement in frequency of hairball upchucks since I started brushing all three on a regular basis, approximately 2 times a week. Daily would probably be better, and I am going to try to get up to every other day at least. Finding the right brush was also very helpful. Most brushes do not seem to pull the dead hair out thoroughly, or they pull too much, and the cat will resist being brushed if the experience is not pleasant. We ended up using a combination of a slicker brush and a rubber bristle brush.
As for the enzymes, we do not use them anymore, which I believe is a testament to how effective a regular brushing routine is for preventing hairballs. It is also a much cheaper option, which is awesome for us with 3 cats and 2 dogs to care for.