I thought it was normal for cats to cough up hairballs? Is this different from vomiting? My cats cough up hairballs 1-2 a month, I have had them on Pro Plan Extra Care Hairball treatment dry cat food for sometime now and at first it was working like a charm however, for the past couple months they seem to still cough up hairballs. But I thought this was normal. They are strickly indoor cats too if that makes any difference.