Small red dots on the top of the skin may be caused by mosquito bites, or it may be caused by folliculitis, allergy, pressure purpura, hemangioma, etc. 1. Mosquito bites: toxic substances remain in the body after being bitten by mosquitoes, which may cause localized red spots, itching and other symptoms. 2. Folliculitis: Hair follicles infected with bacteria produce inflammation, which can cause local skin to appear many small red spots or large papules, mostly accompanied by itching, pain and other symptoms. 3. Allergy: contact with dust mites, willow floss and other allergens can cause allergic allergic reactions, manifested in small red dots on the skin, itching and other symptoms. 4. Compression purpura: rupture of capillaries under pressure caused by multiple factors, blood collects under the skin, manifesting as small red blood spots on the skin. 5. Hemangioma: the formation mechanism is not clear, may be related to multiple factors, manifested as small red dots on the skin, pressing does not fade. If the small red dots appear on the skin for a long time without relief or even aggravation, it is recommended to consult a doctor in time to find out the cause of the disease and actively comply with the doctor’s instructions, so as to avoid delaying the condition.