My son was on decutane when he was 16 his acne has healed totally. would he ever suffer from acne again, could it return when he's older?

Relapse rate varies: According to some studies, relapse of cystic acne (severe form) after Accutane treatment varies widely between 10-50 % depending on several factors of dosage, duration of treatment etc. A rule of thumb is to keep patient on other anti-acne regimens for a longer duration. If your sons acne was milder, and has no scars on the skin, he is probably cured for life:) Pl check the attached article.