Small red pimples on the neck, may be urticaria, folliculitis or contact dermatitis and other skin diseases. 1. Urticaria: If solar urticaria occurs, due to the interaction between mast cell surface receptors and ligands during physical factors of sunlight irradiation, erythema or doughnuts may appear in sun-exposed areas, mostly accompanied by itching and stinging, which may subside after 1 to 2 hours. 2. Folliculitis: when there is high temperature and excessive sweating, poor hygiene habits or long-term application of glucocorticoids, etc., it can be induced by Staphylococcus aureus, Staphylococcus epidermidis and other infections of hair follicles, resulting in the appearance of red pimples on the neck, head and face, and pustules can subsequently appear. 3. Contact dermatitis: when the neck skin mucosa contact with certain exogenous substances such as cosmetics, necklaces and other items, can appear in the contact area of the red papules or mounds of herpes, severe redness and swelling is obvious, blisters or blisters can be formed. It is recommended that when more red pimples appear at the neck, go to the hospital specialist in time, clarify the cause of the lesions, and then follow the doctor’s instructions for symptomatic treatment.