“Small particles” that is, pimples, buttocks have dense pimples very itchy, consider and eczema, contact dermatitis, etc., can be treated by drugs. 1. Eczema: If the patient consumes allergy-prone food, such as sea fish, crab, mango, etc., may stimulate the patient’s body immune function, causing eczema, resulting in dense pimples on the buttocks is very itchy symptoms. Patients can follow the doctor’s instructions for external glucocorticoid cream treatment, such as mometasone furoate cream, can play a role in inhibiting the immune inflammatory response. 2. Contact dermatitis: If the patient’s buttocks skin has been in contact with certain stimuli, it may cause contact dermatitis, appearing buttocks have dense pimples and itchy situation. Patients need to stop contact with the stimulus, can follow the doctor’s instructions for external use of immunosuppressive cream such as tacrolimus cream treatment. If there are dense pimples on the buttocks and itchy situation, it is recommended that the patient go to the hospital, under the guidance of the doctor’s treatment.