Erosive blisters are herpes that rise above the skin and contain watery fluid. Blister formation is mostly the result of inflammatory reactions, such as those caused by bacteria, viruses, parasites (scabies), or allergic reactions, and commonly includes aspergillosis, herpes-like dermatitis, and herpes zoster. The lesions of pemphigus are characterized by large blisters on normal-looking skin and mucous membranes with epidermal peeling, occurring in the folds of the skin, and are most often seen in middle-aged people. Herpes-like dermatitis and herpes zoster, on the other hand, are polymorphic lesions. So, what tests should be done for erosive blisters? Polymorphic lesions refer to the variety of rash patterns. For example, in herpes-like dermatitis, in addition to blisters, there are many kinds of damage such as erythema, papules, and windbags, and itching is intense, but mucous membranes are not damaged, and the lesions tend to occur in the armpits, shoulders, and arms. Another example is chickenpox, which starts as a papule, then blisters, oval-shaped, and finally crusts and flakes, characterized by the presence of various stages of rash, i.e., papules, herpes, and crusts at the same time, with a centripetal distribution, more on the trunk than on the extremities. Herpes zoster is a type of herpes caused by the varicella virus. The lesions are characterized by clusters of blisters distributed in bands along the peripheral nerves on one side of the body, accompanied by neuralgia and local lymph node enlargement. Generally, herpes zoster is immune for life, meaning that recurrences are rare after healing. Advanced visceral cancers also present with herpes zoster, but they are recurrent and systemically disseminated, so it is especially important to be aware of this situation. It has been observed that when herpes zoster is present in cancer, the patient mostly dies within six months. Polymorphic lesions are also seen in systemic lupus erythematosus, where erythema, papules, blisters, petechiae, vesicles, and ulcers can be seen, while butterfly-shaped erythema on the face is its characteristic feature.