Papular urticaria can cause swelling of the back of the feet. Papular urticaria is a disease in which localized edema is caused by insect bites that cause localized dilation or abnormal increase in permeability of small blood vessels in the skin and mucous membranes. If the feet are bitten by insects, the local skin tissues and blood vessels may be abnormally dilated or increased permeability, which will lead to the phenomenon of local soft tissue edema, which can be manifested as dorsal swelling. In addition, some patients may have clustered or scattered pimples or papules with severe itching, fever and other symptoms, and in severe cases, shock may occur. When the body appears uncomfortable symptoms, need to go to the hospital in time for examination, under the guidance of professional doctors to carry out targeted treatment, to reduce the impact on the body.