<prompt> Recalcitrant acne is treated by:Oral erythromycinOral tetracyclineRetinoidsSteroids  <response>: The European S3 guidelines recommend isotretinoin for the treatment of severe recalcitrant acne or moderate acne that has failed to respond to conventional antibiotic therapies. Retinoids - Isotretinoin : D.O.C for severe gd 4 nodulocystic acne acne conglobata. Dose 0.5 - 1 mg kg body weight to be given till cumulative dose of 120-150mgkg body weight. 