Three Major Reactions to Urticaria

1. allergic reaction

2. immune response to infection

3. autoimmune reaction

Allergic Reaction

If urticaria is Anaphylaxis Sometimes, patients develop urticaria within about one to two hours after being exposed to allergens (such as drugs, food, or insects). For example, some people are allergic to seafood such as shrimps and crabs. Whenever they eat such foods, the rash will gradually disappear within a day. When they come into contact with the same food again, the rubella will reappear.

Sometimes, patients may not be fully aware of their feelings about a serious Anaphylaxis. Some people may be allergic to food additives or seasonings such as ginger and garlic. Food allergies often trigger acute urticaria.

Environmental allergens can also cause acute urticaria. For example, people with animal allergies will develop urticaria after contact with cats and dogs. People with dust mite allergies or people with nasal allergies or asthma will develop urticaria after contact with dust or dusty objects, or when they wear sweaters that have not been washed for a long time. Learn about allergy testing.

Immune Response to Infection

Parasitic infections are the main cause of urticaria in some backward countries. However, in more advanced places like Hong Kong, there are also chances of being infected by parasites, such as eating raw fish and keeping pets at home. Children are most susceptible to parasitic infections due to lack of awareness of hygiene.

The more common viruses that cause gastroenteritis are norovirus and rotavirus, so patients with gastroenteritis are more likely to develop urticaria at the same time; in addition, some long-term virus carriers such as hepatitis are more likely to develop urticaria, which will last for a period of time until the hepatitis is cured.

Autoimmune Reaction

Autoimmunity refers to the immune response produced by the immune system against self-organized tissues, producing antibodies and immune cells to attack body tissues, eventually causing autoimmune diseases. There are many types of autoimmune diseases, the most familiar ones being rheumatoid arthritis and lupus erythematosus. People with the above two systemic immune diseases are prone to develop urticaria, but such patients account for less than 2% of the overall chronic urticaria.

Studies have found that about 60-70% of patients with chronic urticaria have allergic reactions to their own serum, that is, antibodies against immunoglobulin E (IgE) receptors can be found in the patient's serum, and these antibodies can cause mast cells to become active, release histamine, and cause urticaria. This type of chronic urticaria can be diagnosed with autologous serum skin testing.