Thank you for your question.
If cystic acne is not responding to oral antibiotics and topical benzoyl peroxide, oral isotretinoin is a good option as this is a very effective treatment for cystic acne.
Intralesional steroid injection is a good option to consider too for cystic acne. It helps to quickly reduce the inflammation and size of the cysts. This treatment can be used together with oral antibiotics or isotretinoin which help to prevent new cysts from developing.