Can I combine flea meds after giving my dog expired Comfortis?
Hi,
The truth about expiration dates is that they are usually not based on any studies and the drug is likely to be just as effective years after. I can't say for sure, but it's likely that Comfortis will work. However, the fleas should all be dead within 24 hours, so if you are still seeing live ones jumping around, then it likely didn't work well.
You can definitely use the flea collar with Comfortis and this may help to rid her of the remaining fleas. I recommend waiting another week after applying the collar to assess if the treatment worked.
If you are still seeing fleas crawling around, then you can try a different flea product like Frontline. Avoid any products that contain ivermectin or any other avermectins for at-least 4 weeks after giving the Comfortis - you can check for this by looking at the active ingredients on the package...any name that ends in "-mectin" should be avoided.
I hope that helps and Maggie if flea-free soon.
Updated on September 23rd, 2025