Natural soap compositions and methods of manufacturing the same having anti-microbial properties for treating and preventing diaper rash and other microbial infections. The soap compositions may contain one or more fatty acids with carbon length ranging from four (C4) to twenty-two (C22) and/or natural fatty acid mixtures of coconut oil, olive oil, and/or tall oil fatty acids which are saponified with lye. The saponification lye may be sodium or potassium hydroxide. In preferred embodiments, the soap compositions contain at least one of sodium or potassium caprate, sodium or potassium caprylate, or mixtures thereof, especially 55:45% caprylate to caprate. The soap compositions are effective at treating or preventing diaper rashes and other microbial infections associated with Candida albicans (Ca—yeast), Pseudomonas aeruginosa (Psa—a Gram negative bacteria), Staphylococcus aureus (Sa—a Gram positive bacteria), and Aspergillus niger (An—a mold).