My Alex is finishing his 8th month with his collar and it has been worth every dollar. I was able to get it for 49.00 plus 20.00 rebate cost came out to 29.00 and free shipping with Dr. Foster's I believe.
In 8 months I found 2 dead ticks on his legs and nothing else. I kept the collar really loose so I could pull it off when I needed the harness or a collar for outings. His new one goes on Nov.1 for the next 8 months.
No side effects of any sort. A big money hassle saver and I definitely recommend.