Is castor oil good for sebaceous cysts?

I doubt it: I can't imagine how this could help but there are numerous anecdotal reports of it helping sebaceous cysts to drain. Chronic sebaceous cyst frequently drain and resolve temporarily but then what recur. For recurrent sebaceous cyst the only effective treatment I have seen is excision of the entire cyst lining.

Infected?: Abx will NOT cure a sebaceous cyst. They can help clear the infection and surrounding cellulitis that can occur when the cyst becomes infected. .... but not the cyst itself. The cyst needs to be removed if bothering you. If not bothering you can be safely watched.