The instant invention relates to a semi-solid topical composition containing Pirfenidone and an antimicrobial/antiseptic agent such as Modified Diallyl Disulfide Oxide (M-DDO) and its preparation process, offering advantages compared to other pharmaceutical forms of topical administration known in the state of the art, useful as antifibrotic, anti-inflammatory and antiseptic agent in the prevention, treatment and reversion of acne and post acne lesions. Said compositions is also useful for reducing skin redness, detaining the formation of new acne outbreaks, reversing already existing outbreaks and regenerating skin damage caused by acne.