What would cause a sudden blister in an already infected leg?

Hi,

Welcome to icliniq.com.

I went through your query and understood your concern.

This is a furuncle-bacterial infection (Staphylococcus and Streptococcus bacteria cause this infection) of hair follicles with inflammation of surrounding skin that forms a painful papule (bump). Later it gets filled with pus and tissue fluid mixed with blood. This requires oral antibiotics and topical antibiotic cream or ointment as treatment. Doxycycline is an antibacterial drug that works against Streptococcus and Staphylococcus bacterial infections and should help resolve this furuncle.

So along with the tablet Doxycycline, I suggest you to apply topical Mupirocin (topical antibiotic) 2 % ointment on the affected area two times a day for 10 to 14 days. Also, the area should be cleaned with a warm saline solution with gauze before applying Mupirocin ointment.

Kindly consult a specialist, talk with them and take the medications with their consent.

I hope this helps.

Take care.