Painful lip blisters are mostly caused by herpes virus infection, bacterial infection, etc. They can be treated by using antiviral drugs and antibacterial drugs to treat the cause. 1. Antiviral drugs: Lip blisters caused by herpes virus infection can be treated with oral acyclovir tablets, vasiclovir tablets, etc., or topical acyclovir ointment can be applied for treatment. 2. Bacterial infections: mostly caused by streptococcal infections or staphylococcal infections, you can take oral cephalosporin antibiotics, such as cefixime, cefuroxime, etc., but also local topical erythromycin ointment, mupirocin cream and so on. These drugs have different degrees of adverse reactions, such as gastrointestinal irritation, liver and kidney toxicity, allergy, etc. It is recommended to consult a doctor in time and use drugs under the guidance of the doctor.