The skin becomes red and purple after breast cancer radiotherapy, which may be the side effect of radiotherapy, skin protectant, antibiotic ointment and itch-relieving and pain-relieving ointment should be applied under the guidance of professional doctor. 1. Skin protectant: 2 hours before the radiotherapy for breast cancer, skin protectant, such as Biafin or Radiotherapy Ointment, should be used under the guidance of professional doctors and applied to the area of radiotherapy. After radiotherapy, skin protectants should also be applied to prevent dermatitis and reduce the symptoms of red and purple skin after radiotherapy. 2. antibiotic ointment: if the skin becomes red and purple after breast cancer radiotherapy, accompanied by the symptoms of skin infection, you can apply antibiotic ointment, such as mupirocin and erythromycin. 3. Itch-relieving and pain-relieving ointment: If the skin turns reddish purple after breast cancer radiotherapy, accompanied by itching and pain, you can apply itch-relieving and pain-relieving ointment, such as zinc oxide, burn cream, etc., and use it alternately with skin protectants. Once the skin becomes reddish purple after breast cancer radiotherapy, it is recommended to give timely feedback to the attending doctor and use medicated ointment under the doctor’s guidance for good skin protection.