Abstract This paper describes the association of two unusual side effects of treatment with isotretinoin for severe acne: paronychia and excess granulation tissue in the nails furrows. We report a case of male patient aged 19 years, who in the course of the 36th week of treatment with isotretinoin for acne grade III showed erythema, edema, excess granulation tissue and onychocryptosis in various nail beds of hands and feet, with no history of trauma associated. A literature review revealed few reports of these adverse events, and two clinical patterns of exuberant granulation tissue has been described: one in periungual location and other in lesions of previous acne. The rarity and lack of knowledge on the best treatment for granuloma-like reactions make this theme a considerable challenge.