Hi,
It is highly unlikely that isotretinoin will fail to result in any improvement in cystic acne if adequate dosing is used.
A higher dose of 0.5-1mg/kg/day may be needed to suppress more recalcitrant cystic acne. Sometimes it may take up to 6 months before the inflammatory acne can be fully controlled.
At the same time, complications of gram-negative folliculitis requiring the use of appropriate oral antibiotics need to considered.
Adjuvant treatment such as intralesional steroids and hormonal therapy (in females) may give additional benefits. A healthy lifestyle reducing stress and avoiding high glycaemic index foods and excessive dairy products will also help control acne better.
A regular review by your attending doctor will definitely help sort out the various issues highlighted above.
Hope this helps!
