She's always gone in cycles about it. I get her clear for several months and then they crop up again. At one point the vet and I were considering what is essentially kitty xanax for her anxiety, but I couldn't do it. The pheromone collar helps if she leaves it on, but she doesn't. Both my kitties are collar-removing pros. The pheromone plug in did pretty much nada, as I guess it needs to be right in her face. Jackson Galaxy Spirit Essences helped a little, maybe, but are hella expensive, and rescue remedy didn't do much. So we cycle.