The possible clinical causes of red pimples on the neck and chest are folliculitis, eczema and acne. 1. Folliculitis: this condition is usually associated with inadequate body cleansing. Inflammation occurs when the skin follicles become clogged and infected by bacteria and other pathogenic microorganisms, with clinical manifestations such as red pimples, itching, pain, and pus on the affected skin. 2. Eczema: part of the population is more sensitive, in contact with a variety of factors inside and outside the stimulation of the body skin prone to allergic reactions, the clinical manifestations of the affected areas of the skin appeared red, itchy, pimples and so on. 3. Acne: This is a chronic inflammatory disease that occurs in the sebaceous glands of the hair follicles, which is associated with androgen abnormalities, exuberant secretion of sebaceous glands and bacterial infections, etc. Clinical manifestations are pimples, pustules, acne, etc., in the affected area of the skin. It is recommended that people with related conditions should go to the dermatology department of the hospital for consultation, so as to carry out targeted treatment.