- home remedies for hives urticaria - medical home remedies urticariabr br What causes hives and angioedema?br br Hives are produced when histamine and other compounds are released br from cells called mast cells, which are normally found in the skin. br br Histamine causes fluid to leak from the local blood vessels, leading to swelling in the skin.br br Hives are very common. Although they can be annoying, they usually resolve br on their own over a period of weeks and are rarely medically serious. br br Some hives are caused by allergies to such things as foods, medications, br and insect stings, but in the majority of cases, no specific cause for them is ever found.