Small red dots on the neck at several points of the day, may be the emergence of eczema, prickly heat, allergic dermatitis and other diseases. 1. Eczema: a wide range of morbidity, to long-term recurrence of skin inflammation itchy skin disease. The specific cause of the disease is unknown, but can be related to immune system disorders, mental stress and other factors. Often distributed in the head and face, hands and feet, neck and other locations, manifested as erythema, papules, blisters, etc., and in severe cases, there may be redness, swelling and erosion. 2. Prickly heat: It is a skin disease caused by the blockage of sweat ducts, high ambient temperature and breathable clothes in a hot environment. Prickly heat occurs in the folds of the skin, such as the neck or back, and is mainly manifested as pinpoint-sized, superficial blisters, which can be blister-like or red dotted. 3. Allergic dermatitis: it is a kind of allergic disease caused by the stimulation of allergens. When the neck comes into contact with necklaces and other allergy-inducing things, it can appear in patches of red dots and be accompanied by itching, pain and even erythematous blisters and other symptoms. It is recommended that patients go to the dermatology department to identify the cause of the disease and then targeted treatment.