Dense red dots on the arms and back may be caused by eczema, contact dermatitis and other diseases, patients can take medication, general treatment and other therapeutic measures. 1. Eczema:Eczema patients will appear erythema, corn-like size papules, vesicles and other symptoms, patients can follow the doctor’s instructions to use Dinaid cream, hydrocortisone butyrate cream and other topical glucocorticosteroid cream for treatment, you can also use boric acid solution, esacridine solution and other topical lotion treatment. In addition, patients can also take oral loratadine tablets, cyproheptadine tablets and other antihistamines for treatment. 2. Contact dermatitis: the main symptoms of contact dermatitis are erythema, pinpoint-sized dense papules, itching, etc. Patients can follow the doctor’s instructions to use mometasone furoate cream, tretinoin econazole cream and other glucocorticosteroid cream treatment, but also oral chlorpheniramine maleate, benzydamine hydrochloride tablets and other antihistamines. Patients with symptoms of dense small red dots on the arms and back should seek medical attention to identify the cause of the disease and follow the doctor’s instructions for treatment.