I don’t use the flea collar on advice of the vet. A friend of mine’s dog began having seizures daily & after many expensive tests with no definitive result, the vet suggested he take off the flea collar to see what would happen. After about 3 days with NO flea collar the seizures suddenly stopped.
For years I used the going flea meds recommended by my vet…the one where you put a few drops between their shoulder blades once a month. Last year that just completely stopped being effective. At the time I was getting into essential oils & I found an EO spray that claimed to rid my dog of fleas & decided to try it to see IF it would work. It wasn’t an easy fix; but after spraying my dog several times a day, he had NO fleas & I started spraying him less & less. I’ve also read that you can use Lavender EO on their bedding to help keep fleas off of them.
You might start with taking your dog to the vet for a flea dip & then choose a preventative to keep it free of fleas. I just would NOT use a flea collar!!!