The first, and most basic, step to help reduce the risk of hairball formation in cats is frequent brushing. By brushing away loose hair, you can reduce the amount of hair your cat will ingest. Therefore, you also reduce the chance that the hair will gather in the digestive tract.
Some cats groom themselves and their housemates. Therefore, it’s a good idea to brush all the cats in your house. Baths or professional grooming during a change in season help by ridding the cat of the loose hair from normal, seasonal shedding.