The common causes of urticaria include fish, shrimp, crab, meat, eggs and other animal protein foods; vegetables and fruits such as eggplant, bamboo shoots, spinach, apples and plums; pollen, animal dander, feathers and other inhalants, as well as various acute and chronic infections, medications, insect bites, etc. Urticaria often starts with itchy skin, followed by wind clusters that are bright red or pale, skin-coloured. In a few cases there may be oedematous erythema.
If the itching persists on the back of the foot without relief, prompt consultation with a dermatologist is required to avoid delay.