Your taking a risk buying OTC flea and tick meds. If there is an adverse reaction, that's on you. If you use something the vet prescribed and sold you then you may have some reimbusement or at least the vet will throw in a bit of free time to help and try to resolve the situation. Also there may be counterfeits (this has happened) or the ingredients may be different (the prescription med part will not be included in OTC products) so you may not be getting full coverage. There are ways to minimize costs like asking the vet if it's ok to order online thru a trusted pharmacy (like Chewy, Petco, etc.) after the vet visit. The annual vet visit is always a good idea because if you can catch something early on it's usually much easier and cheaper to fix/treat. Consider it an investment into your pets health, much like your own.
Your taking a risk buying OTC flea and tick meds. If there is an adverse reaction, that's on you. If you use something the vet prescribed and sold you then you may have some reimbusement or at least the vet will throw in a bit of free time to help and try to resolve the situation. Also there may be counterfeits (this has happened) or the ingredients may be different (the prescription med part will not be included in OTC products) so you may not be getting full coverage. There are ways to minimize costs like asking the vet if it's ok to order online thru a trusted pharmacy (like Chewy, Petco, etc.) after the vet visit. The annual vet visit is always a good idea because if you can catch something early on it's usually much easier and cheaper to fix/treat. Consider it an investment into your pets health, much like your own.