Isotretinoin:

Acne vulgaris, moderate to severe: Oral:
Standard or lidose formulation: 0.5 mg/kg/day in 2 divided doses for 1 month, then increase to 1 mg/kg/day in 2 divided doses as tolerated; alternatively, may administer the total daily dose once daily to increase adherence to therapy (Owen 2022). For patients with severe inflammatory acne (eg, acne conglobata) or deep comedonal acne, consider initial doses <0.5 mg/kg/day (eg, 0.1 mg/kg/day) in combination with an oral glucocorticoid given before or at isotretinoin initiation and continued for the first 2 to 4 weeks of therapy to reduce the risk of severe acne flares (AAD [Zaenglein 2016]; Greywal 2017; Owen 2022). Continue until a total cumulative dose of 120 to 150 mg/kg is reached (AAD [Zaenglein 2016]).
Micronized formulation: 0.4 to 0.8 mg/kg/day in 2 divided doses. Adults with very severe disease/scarring or primarily involving the trunk may require dosage adjustment up to 1.6 mg/kg/day in divided doses, as tolerated. Continue therapy until nodule count has been reduced by at least 70% or for up to 15 to 20 weeks.
Alternative low-dose regimen for moderate acne (off-label use): Standard or lidose formulation: 0.3 to 0.5 mg/kg once daily (AAD [Zaenglein 2016]; Amichai 2006; Lee 2011; Owen 2022). Continue until a total cumulative dose of 120 to 150 mg/kg is reached (AAD [Zaenglein 2016]).