Acne around neck after breast cancer chemotherapy is usually caused by cumulative drug reaction, endocrine disorders, allergy, etc. Cumulative drug reaction and endocrine disorders can be treated by drugs, and allergy can be treated by drugs and surgery. 1. Cumulative drug reaction: If the patient undergoes chemotherapy for breast cancer for many times, it may produce cumulative drug reaction and skin rash, resulting in acne and ulcers around the neck and other symptoms, leading to acne around the neck after chemotherapy for breast cancer. 2. Endocrine disorders: chemotherapy for breast cancer may cause endocrine disorders, loss of appetite and other side effects, which will lead to acne on the neck, dark color and other symptoms, resulting in acne around the neck after chemotherapy for breast cancer. Hydrocortisone, insulin and other medicines can be used to alleviate the adverse reactions of endocrine disorders, and are forbidden to those who are allergic to the medicines. 3. Allergy: if patients are allergic to breast cancer chemotherapy drugs, it will lead to itching and acne at the back of the neck, resulting in acne around the neck after breast cancer chemotherapy, you can take budesonide aerosol, fluticasone propionate and other medicines to alleviate the allergic symptoms of the patients, which is beneficial to the recovery of the disease, and is prohibited for those who are allergic to the drugs, and if there is a situation of serious edema of the larynx, you can have a tracheotomy. The patient is recommended to go to the hospital for examination in a timely manner. It is recommended that patients go to the hospital for examination in time, pay attention to the care of the body as well as a healthy diet.