If there is a bump on the skin after the injection, it may be due to the following reasons: 1. It may be caused by the local drug deposited in the subcutaneous tissue. This situation can generally be given a local hot compress or local rubbing, after the drug dissipates and absorbs, it can disappear immediately. 2, there may be a local needle mouth where there are symptoms of skin allergy. It is common to be allergic to the injected drug or to the disinfectant solution used for disinfection, such as iodophor or alcohol, resulting in a local rash like a windbreak. In this case, the symptoms are mainly itchy. 3. It is possible that the puncture needle may have led to the rupture of the subcutaneous capillaries and bleeding after the puncture, resulting in the formation of a small local hematoma.