Sebaceous cyst inflamed dangerous?

Not if it is treated: Properly using apropriate antibiotics and surgical drainage when necessary, assuming normal immune function. Show it to a doctor for specific advice.

No: If it does not drain by itself you may be able to squeeze it out. Your dr can open ; drain it if needed. An antibiotic is of no value unless there is spreading infection. It does not matter what you put on it.

Not really but..: 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.