When my outdoor cats had ringworm, the stuff the vet gave me did not work. I mixed 1 part lavender essential oil, 1 part tea tree essential oil and 2 parts olive oil into a jar. Twice a day I applied this to the cats' ringworm spots. I did this for 2 weeks. (Cotinue to treat for a few days even after it looks healed. ) Apparently essential oils can be too strong for cats, so I diluted it, and my cats had no problem. I was sure it was safer than the vet prescription anyway. I used this same thing on my children when they got ringworm from the cats.