Mixed
I have used both pills and diffuser. Seem to work, tho diffuser seems more effective. My dog, who is a major terrier barker, seems to be barking much much less, but we haven't used it very long, and use it off and on so I do wonder if I am hearing what I want to hear! We are noticing that the diffuser got very hot after 8 hours, so we don't intend to leave it in for very long or when no one is home.