The use and long-term benefit of isotretinoin

Isotretinoin is effective in the treatment of acne, but at low doses (0·1 mg/kg) many patients relapse. Over the past 5 years we have treated 250 patients with either 0·5 mg/kg or 1·0 mg/kg of isotretinoin and have followed them up for up to 3 years to determine the relapse rate. All patients in each dose group responded well, with a 90% improvement in acne grade. The majority (86%) needed only 4 months'treatment, but 13% needed 6 months, and two patients required 9 months of continuous therapy. Patients with marked mucous membrane side‐effects tended to respond better than those without such side‐effects. The relapse rate in the 0·5 mg/kg group was significantly greater (42%) than in the 1·0 mg/kg group (13%) (P < 0·01); relapse was defined as the need for further oral therapy—either antibiotics or isotretinoin. Truncal acne was more likely to relapse than facial acne (P < 0·05). Younger patients relapsed more quickly than older patients (P < 0·05). Patients treated with isotretinoin fell into one of five categories: (i) severe acne with isotretinoin as first‐line therapy (18%); (2) failure to improve on conventional antibiotic therapy (55%); (3) rapid relapse after two courses of conventional antibiotic therapy (21%); (4) Gram‐negative folliculitis (3%); and (5) severe psychological disturbance about minor degrees of acne that normally would not require isotretinoin (3%). We thus recommend 1·0 mg/kg as the best dose of isotretinoin for long‐term benefit in acne, and that isotretinoin should now be considered as part of the treatment for less severe types of acne.