The appearance of a large number of red rashes at the joints may be related to contact dermatitis, eczema, allergic purpura and other causes, which need to be analyzed according to the symptoms.
1. Contact dermatitis: contact with allergenic substances such as ointment at the joints can cause abnormal immune response of the body, resulting in localized erythema similar to the shape of the contact material, and a large number of red papules and papules can appear.
2. Eczema: under the action of internal and external factors such as mental tension and external stimulation, it can cause inflammatory reaction at the joints, and a large number of red rashes appear, which can be accompanied by itching and pain.
3. Allergic purpura: it is a kind of IgA type antibody-mediated allergic reaction of capillary and small vasculitis, which can be manifested as the purpura of both lower limbs from the tip of a needle to the size of a soybean, and it can be characterized by palpability, and there can be petechiae, which can be manifested as a large number of red rashes at the joints.
There may also be other reasons for the appearance of a large number of red rashes at the joints, it is recommended to go to the hospital in a timely manner, to clarify the cause of the disease, and standardized treatment under the guidance of the doctor.