Blisters after a spider bite should be assessed by a doctor, as the severity and treatment depend on the type of bite and your individual reaction. Soframycin is an antibiotic cream that helps prevent or treat certain bacterial skin infections, but it may not be sufficient or appropriate for spider bite blisters. Medical evaluation is recommended for proper treatment. Seek urgent care if you develop severe pain, spreading redness or swelling, fever, breathing difficulty, or other worsening symptoms.