There are many reasons for pimples on the waist, such as herpes zoster, viral warts, folliculitis, allergic factors and so on. 1. Herpes zoster: it is caused by varicella zoster virus infection, the early start may lead to pimples on the waist accompanied by itching or pain, and then there will be rashes, blisters, ulcers and so on. 2. Viral warts: Flat warts, common warts and other viral warts caused by human papilloma virus infection may also lead to the appearance of pimples on the waist. 3. Folliculitis: purulent infections of hair follicles caused by bacterial infections can also lead to the appearance of pimples on the waist. 4. Allergic factors: waist skin allergies to food, environment or contacts can lead to an allergic reaction in the skin, such as contact dermatitis, drug rash, insect bite dermatitis can also lead to acne on the waist. Acne on the waist, there may be other reasons, it is recommended to go to the regular hospital examination, clear cause, under the guidance of the doctor standardized treatment.