Itchy red bumps on the arms may be caused by eczema, hives and contact dermatitis, etc. It is recommended that patients take general treatment, medication and other ways to improve. 1. Eczema: itchy red bumps on the arms may be caused by eczema, patients need to keep the lesions clean, to avoid infection of the affected area. It is recommended to choose glucocorticoid ointment applied to the affected area to help anti-inflammatory, such as dexamethasone, mometasone furoate and so on. 2. Urticaria: Urticaria may cause red bumps on the arms and itchy, patients should look for as well as to avoid the causative factors, it is recommended to take oral cetirizine, loratadine and other antihistamines, with anti-inflammatory and anti-itching effect. 3. Contact dermatitis: contact dermatitis may cause red bumps on the arm, patients should be clear about the cause of the disease, avoid contact with irritants, sensitizers. Patients can use topical hydrocortisone, dexamethasone and other glucocorticoid drugs, oral loratadine and other antihistamines, can reduce inflammation, stop itching. There are many reasons why red bumps on the arm are very itchy, it is recommended that patients seek medical examination to clarify the cause of the disease, follow the doctor’s instructions for medication, do not self-medication.