Acne in the deltoid area may be acne, a common chronic inflammatory disease of the sebaceous glands of the hair follicles. If acne in the deltoid area is accompanied by itchy symptoms, it may also be caused by mosquito bites, which should not be scratched to avoid bacterial infection. Excluding mosquito bites, the facial triangle is richer and more developed in the sebaceous glands of hair follicles, so acne is more likely to occur. The common causes include the following: 1. The endocrine system is responsible for generating and secreting various hormones, which play a very important role in maintaining normal bodily functions, and if hormone secretion is imbalanced, it will seriously affect normal metabolism and have an impact on the body. The most obvious symptom of androgenic activity in adolescent groups and endocrine disorders is that it leads to skin acne; 4. Inadequate skin cleaning: not paying attention to facial skin cleaning, hygiene, oil, dirt clogging follicular pores, may also lead to acne in the facial triangle. Patients should carry out regular diet and rest on a daily basis, pay attention to the regulation of endocrine levels, and avoid eating greasy, spicy and stimulating foods, such as fried things, chili, raw garlic, etc. They should also pay attention to skin cleanliness and should not squeeze with their hands to avoid leaving acne marks or causing infection.