Hi Stacy, this is Linda, a small animal vet.
When it comes to flea and worm medicine, there are some options available over the counter.
Many are ineffective, but some are actually very worthwhile.
For fleas, anything containing Imidacloprid (like Advantage spot on) works very well. You can get this without a vet visit or prescription.
If fleas are an issue, we want to treat all household pets and the home at the same time.
This means hot washing all bedding, daily hoovering and using a flea spray that contains an insect growth regulator (no prescription needed).
Wormers are readily available over the counter, and we should opt for broad acting ones, particularly if the cat goes outside. Any containing Fenbendazole are freely available and work well.
So, in general, no need to see a vet. This is assuming your cat is in good health and you know their weight.