Red spots on the chest and back may be caused by atopic dermatitis, folliculitis, eczema and other reasons . 1. Allergic dermatitis: If allergy-prone people come into contact with allergens, such as dust, pollen, animal fur and other substances will lead to skin allergies, resulting in red spots on the chest and back. 2. Folliculitis: when the body oil secretion is exuberant so that the pores are clogged, infected with bacteria, it is easy to form folliculitis, which leads to the appearance of red pimples on the chest and back, that is, manifested as small red dots, the pimples can be accompanied by a sense of pain. 3. Eczema: Eczema is generally due to a variety of causes of skin inflammation, easy to recur, which will lead to the appearance of red spots on the chest and back. It is recommended that patients with red dots on the chest and back go to the hospital in time to clarify the cause of the disease and then actively treat it.