Itchy bumps on arms and thighs may be caused by hives, folliculitis, contact dermatitis and other diseases. 1. Urticaria: The cause of urticaria is mostly related to food allergy, drug allergy, infection and other factors. Patients can appear, the size of the wind, the wind of different, can be round, oval or irregular, accompanied by obvious itching symptoms, manifested in the arms of the thighs itchy pimples. 2. Folliculitis: Folliculitis may be caused by skin trauma, bacterial infection, excessive sweating, poor hygiene habits and other factors. Patients can appear in the thighs, arms, pimples, pustules, itching, pain and other symptoms, some patients will show a small bumps and itching. 3. Contact dermatitis: contact dermatitis is mainly caused by skin contact with exogenous substances that irritate the skin, thus causing a series of symptoms. Symptoms of erythema, papules, edema, itching, etc., patients can appear in the arms and thighs of small bumps, and accompanied by itching symptoms. There are many reasons for the itchy bumps on the arms and thighs, so it is recommended that patients find out the cause of the disease in time and actively take relevant treatment measures.