For cat ringworm, should you use alcohol or iodine?

For treating cat ringworm, neither alcohol nor iodine works well, because both are mainly for infections caused by susceptible bacteria and have little effect on fungal infections, so they cannot cure ringworm. Ringworm is usually caused by fungi such as Microsporum, and is generally treated with medications containing itraconazole, terbinafine and similar ingredients. If you find your cat has ringworm, use an antifungal medication promptly to prevent the infection from worsening.