Itchy bumps on the joints when they are hot may be caused by cholinergic urticaria, solar dermatitis and other skin diseases, which are mostly treated with medication. 1. cholinergic urticaria: a type of urticaria, with very itchy dot-like wind as the main symptom, and sports, hot weather, spicy food or hot baths, etc., the above factors make the skin local temperature rise to the joints pimples itchy heat. Treatment should be the first to remove the causative factors, and at the same time, follow the doctor’s instructions for external use of glycerite lotion, oral antihistamine drugs such as ebastine tablets. 2. Solar dermatitis: also known as acute sunburn, sunburn, is the skin to receive strong light exposure caused by an acute injury to the skin reaction, can appear in the exposure site erythema, papules, can be accompanied by intense itching and burning sensation. Often external glycerine lotion, glucocorticoid ointment, oral non-steroidal anti-inflammatory drugs, antihistamines and so on. It is recommended that patients with hot and itchy bumps on the joints should go to a regular hospital for consultation and targeted treatment after a clear diagnosis.