Let’s first look at the staging of hives: acute? Or chronic? According to the duration of the onset of urticaria, it can be divided into.
1. acute urticaria: rash lasting less than 6 weeks.
2. Chronic urticaria: rash lasting longer than 6 weeks.
Although we artificially stage urticaria according to the duration of onset, most acute urticaria heals in about 2 weeks. If the urticaria lasts for 3-4 weeks, it is still chronic urticaria in terms of trends, although it does not meet the criteria of chronic urticaria lasting more than 6 weeks.
Why is it necessary to stage urticaria? This is mainly because the causes or triggers of acute urticaria and chronic urticaria are quite different and have a different impact on the patient’s quality of life, while the treatment strategy will be different.
Urticaria = allergy ? No!
Infection is the most common trigger of acute urticaria The following chart shows the distribution of common triggers of acute urticaria. It can be seen that of the patients with acute urticaria for whom a cause can be found (please note that about half of the patients with acute urticaria have difficulty finding a definite cause), infection is the predominant trigger.
Infections
Infections can cause acute urticaria. In fact, viral infections are probably the cause of most acute urticaria in children. A variety of viruses can induce acute urticaria (including the common cold virus).
Infection-associated urticaria usually appears when the immune system begins to clear the infection, sometimes a week or more after the onset of the infectious disease, and the rash usually lasts a week or two before disappearing.
Medications
A variety of medications can cause acute urticaria, the most common being antibiotics and antipyretics (also commonly known as antipyretics and analgesics such as aspirin, ibuprofen and naproxen), analgesics (such as codeine and morphine), muscle relaxants used for anesthesia and contrast agents used to perform imaging tests can also trigger acute urticaria.
Mosquito bites
Certain insect bites such as bees, wasps, and red ants can produce hives at the site of the bite. If there are more bites (e.g., stabbing a hornet’s nest), it is possible to induce acute urticaria all over the body, and in severe cases, anaphylaxis may also occur (this condition requires a visit to the hospital as soon as possible).
Food allergy
Food allergies may lead to acute urticaria. Food-related acute urticaria usually appears within 30 minutes of food consumption. Common foods that trigger urticaria in children are milk, eggs, peanuts, other nuts, soy, and wheat.
Foods most likely to trigger acute urticaria in adults are fish, shellfish, peanuts, and other nuts.
Other exposure factors
Acute urticaria can also be triggered by exposure to allergic substances through other means. For example, a child who is allergic to dog dander may develop hives after playing with or being licked by a puppy. Other things that can trigger acute hives are some plants, raw fruits and vegetables, and latex (balloons, rubber gloves, condoms, and other rubber products, etc.).
Patients with acute urticaria may experience laryngeal edema or acute anaphylaxis, which can be life-threatening. If the patient provides a history and course highly suggestive of an allergen, the allergen can be identified by skin prick testing and blood sampling for IgE antibodies. The purpose of allergen investigation is to provide clinical evidence for further avoidance of exposure and to avoid subsequent severe systemic allergic reactions.
The vast majority of chronic urticaria is not related to allergies The following figure shows the distribution of common triggers of chronic urticaria, which can be seen as a more complex cause or trigger of chronic urticaria.
Physical
Factors
More than half of all patients with chronic urticaria may be triggered by a variety of physical factors, such as higher temperatures (hot baths) or pressure on the skin surface (belt tightening areas) are some of the more common physical triggers, and other common physical triggers include sunlight, exercise, and cold air and water. If urticaria is primarily triggered by various physical factors, it is also called physical urticaria or inducible urticaria.
Infections
Infected lesions in the body can cause hives to worsen, for example, when suffering from a viral infection (common cold) or a bacterial infection (tonsillitis or sinusitis), the hives rash is often more severe and difficult to control with regular doses of medication.
Medications
Between 20% and 50% of patients with chronic urticaria experience an increase in urticaria symptoms after taking antipyretic drugs, usually within a minimum of 15 minutes and a maximum of 24 hours after taking the drug. Some sedative-hypnotic drugs may also cause exacerbation of chronic urticaria.
Drinking alcohol
Alcohol consumption may trigger urticaria or worsen chronic urticaria symptoms, mainly because of the presence of substances in alcohol or beverages containing alcohol that can directly cause the release of histamine (histamine is the most important inflammatory substance that causes urticaria and can cause skin eruptions, edema and itching).
Dietary habits
Although food allergies (associated with IgE antibodies) are rarely a cause of chronic urticaria, many patients still find that their urticarial rash worsens after consuming certain foods, especially if multiple foods or spicy foods are consumed at once that seem to trigger hives. It is speculated that this condition may be related to the presence of pseudoallergens in food, a class of naturally occurring aromatic substances that are present in varying amounts in many fruits, vegetables and seafood. Artificial colors and preservatives in some processed foods are also pseudoallergens and may cause increased symptoms of hives.
Stress
Many patients will find that their hives symptoms worsen when they experience increased physical or mental stress.
Sleep
Frequent late nights or lack of sleep can also cause hives to worsen.
Female Physiological Periods
Some female patients experience worsening symptoms during their menstrual period, when they need to increase the dose of oral antihistamines to control the condition.
Other co-morbidities
Chronic urticaria may be associated with some autoimmune diseases and thyroid disorders. 9.8% of patients with chronic urticaria also have hypothyroidism and 2.6% have hyperthyroidism. Positive thyroid autoantibodies may be associated with chronic urticaria, and some studies have found that patients with positive thyroid autoantibodies do not respond well to regular doses of antihistamines and have a longer duration of illness.