What if a sebaceous cyst ruptures inside the body? the cyst is soft but very painful- is it dangerous? dr. put me on bactrim (sulfamethoxazole and trimethoprim) 5 days ago. still painful

Inflammation: A ruptured sebaceous cyst will induce inflammation and it would not be affected by antibiotics. If the cyst did rupture as you state, it would be best treated by surgery.

Unlikely: It would be very unusual to rupture inside . It is dependent where it is at. The fact it is soft and painful makes me think of infection. If it is that painful may need opened. See the doctor for further advice

Sebaceous cyst: A sebaceous cyst is contained in the skin. If it ruptures and is infected it may get worse The only way to completely get rid of it it needs to be completely excised. As a rule they are painful and a nuisance but not dangerous

Will not do this.: Trichilemmal and epidermoid cysts may become acutely inflamed. DRAINAGE, spontaneous or surgical, results in relief from pain and eventual healing. They never drain "inside the body" but make a mess out on the skin. Studies indicate that antibiotic therapy only makes the DR feel better, not the patient. Experienced DR's will clean out the entire cyst capsule.