Red dots on the elbow may be caused by mosquito bites, atopic dermatitis or purpura. 1. Mosquito bites: If the elbow appears red dots, localized redness and swelling accompanied by skin itching, no systemic symptoms, may be caused by mosquito bites. If accompanied by dizziness, fatigue and other systemic symptoms, may be caused by toxic mosquito bites, should immediately seek medical treatment. 2. Allergic dermatitis: when contact with allergens, allergic reactions can occur, mainly manifested as red spots on the skin and progressive development, can also be accompanied by respiratory system adverse reactions such as dyspnea, once an allergic reaction occurs, to leave the allergen immediately. 3. Anaphylactic purpura: red dots on the elbows, disappearing when pressed and appearing when not pressed, indicating the occurrence of subcutaneous hemorrhage, may be caused by purpura, and should be immediately referred to the doctor for renal function and coagulation function tests to confirm the diagnosis and timely treatment. Once the elbow with red dots occur, it is recommended to seek medical attention as soon as possible, under the guidance of the doctor for diagnosis and treatment.