Acne Systemic Treatment: Oral Isotretinoin Oral isotretinoin is the standard treatment for severe acne and is currently the most effective treatment for acne. Isotretinoin acts on all pathophysiological aspects of acne pathogenesis, and although the therapeutic effect is significant, it is not used as the first choice of treatment for mild acne as much as possible, considering its adverse effects. Indications for the application of oral isotretinoin: 1. Severe nodular cystic acne and its variant forms; 2. Inflammatory acne with scar formation; 3. Moderate or severe acne that has failed to respond to the following treatments: 3 months of treatment with combination therapy, including systemic application of tetracyclines; 4. Acne patients with severe psychological stress ( disfigurement phobia); 5. Gram-negative bacillary folliculitis; 6. Frequent recurrence of Those who need repeated and long-course systemic application of antibiotics; 7, a small number of patients who need rapid healing for some reason.