How long before ringworm infection starts to visibly improve?
It can take up to a month, but if there is not improvement within a couple of weeks, then a return trip to the vet for a re-diagnosis. It might be more than simply ringworm. I don’t know how the vet diagnosed the ringworm, but a microscope or special light is most often used. Sometimes a culture is also done. While ringworm is common, and obvious, it is not the only thing out there.