Are you sure it is hairballs? I'm just asking because my cat Abby has asthma and when she has an attack she acts like it is a hairball coming up, but nothing comes up. She swallows many times afterwards. Try the hairball remedies, but if they don't help a trip to the vet to rule out asthma might be in order - an asthma attack sounds just like an unproductive hairball session.

For the longest time I wondered why Abby couldn't get her hairballs up, but when I described it to my vet she immediately recognized an asthma attack.