There are no precursors to self-healing hives, but hives can be controlled with treatment and symptoms can disappear completely. If the cause is removed, it will not recur soon; if the cause is not found, it may be easy to recur after stopping the medication. However, in some cases, hives suddenly heal on their own after a period of time. Most hives heal on their own because they have been removed from the allergenic environment, have changed their environment, or have been removed from the allergen automatically for other reasons during this period. About 5%-20% of urticaria can find a specific cause, the vast majority can not find the cause. The most common causes are the following: 1, food: for example, cattle, sheep, shrimp, crab, fish and other high-protein foods; 2, infection: for example, someone has an upper respiratory tract infection or viral infection, bacterial infection, may be induced; 3, plants and animals: animal dust mites, mosquito bites; plant pollen, and animal fur; 4, other infectious factors, systemic diseases: for example, rheumatic fever, other arthritis; 5, physical factors. Overheating, dryness; 6, exposure to certain chemical factors; 7, certain drugs may cause urticaria.