The classic symptoms of urticaria are itchy hives and/or large, swollen areas on the skin (medical term: angioedema). It is generally categorised as either acute or chronic. As a rule, if the symptoms clear within six weeks, it is considered acute. If they last for a longer period, it is considered chronic.
Prevalence in children and adults
Urticaria is a common disease. Acute urticaria occurs in up to 20% of all people during their lifetime. It generally affects all age groups, although it is most frequently observed in children, adolescents and young adults. Chronic urticaria occurs much less frequently. There are no precise figures for the different types of urticaria. But experts estimate that a total of around 1 – 1.5% of the overall population suffers from chronic urticaria.
Causes and triggers
Acute urticaria can be triggered by many different factors such as:
- Acute viral or bacterial infections
- Allergies (for example, allergies to food, bee venom or wasp venom)
The connection between the trigger and the reaction is usually quite clear. However, in about half the cases it cannot be precisely determined.
Chronic urticaria may be triggered by an underlying persistent infection caused by the gut bacteria Helicobacter pylori, Streptococcus or parasites, for example. Other causes include thyroid diseases, an intolerance to the body’s own tissues (medical term: autoimmunity), or allergy-like intolerance reactions (medical term: pseudoallergy). Other chronic forms of the disease are triggered by cold temperatures, heat, the sun or other influences.
But what actually happens in the body at the cellular level? Activated cells in the body’s immune system (called mast cells) release increased levels of histamine, a messenger molecule. This causes the surrounding blood vessels to dilate and become more permeable. Fluid collects in the various skin layers, leading to swelling. In addition, sensory nerves (nerves that transmit sensory stimuli) are activated, resulting in itching and redness. It is not fully understood why the mast cells release more histamine, but there are a number of factors behind it.
The main symptoms of urticaria are hives and angioedema. These can occur at the same time or separately. More than half of acute urticaria patients have both symptoms, while this is true for 40-50% of chronic sufferers.
Hives usually itch and sometimes burn. Angioedema can cause pain as well as itching. The hives normally disappear quickly on their own (after 1 – 24 hours) unlike angioedema, which can last up to three days.
The symptoms of acute urticaria only occur once or several times with a period of up to six weeks. A small percentage of patients go on to develop chronic urticaria, which is by definition when the symptoms last longer than six weeks. The disease can persist for several months, years or even decades, leading to recurring flare-ups. The frequency at which the symptoms recur varies from patient to patient.
Acute urticaria usually resolves on its own and is only treated symptomatically in uncomplicated cases. A doctor can diagnose it based on the patient’s history (medical term: anamnesis) and a physical examination. It is inadvisable to carry out further diagnostic tests at this point. However, further testing may be recommended for infants who may react to certain foods such milk, eggs or peanuts, in order to prevent any severe allergic reactions (medical term: anaphylaxis).
If the symptoms last longer than six weeks (chronic urticaria), the first step is to take a blood sample. Based on the test results, the doctor determines whether there are any signs of inflammation. It is then decided on an individual basis whether further diagnostic tests are required in order to check for underlying causes such as infections or allergies.
If you would like to get involved in research on the causes of your disease, you can visit the website of the Urticaria Network, where you can download an urticaria calendar, an urticaria journal, and an urticaria patient history questionnaire to fill in at your convenience before your doctor’s appointment. This information will help your doctor identify and isolate potential triggers.
The symptoms of acute urticaria can be reduced with antihistamines, which are allergy medicines. If the trigger is known, the patient should avoid it in future (as much as possible).
Antihistamines are also the first line treatment for chronic urticaria. For patients who do not respond well to these drugs, other recently developed medicines are available. If the doctor and patient have managed to identify the trigger, it can be avoided in future and the cause can be treated. There can be very different types of treatment depending on the cause. For a drug intolerance, the patient stops taking the medication as recommended by the doctor or is switched to another medication if necessary. If the patient has an infection, the doctor may prescribe antibiotics. Urticaria is rarely caused by a food allergy or intolerance. Changes to the diet should therefore only be made if recommended by a doctor following a confirmed diagnosis and should be supervised by a qualified nutritionist.
Chronic urticaria may eventually heal on its own even if left untreated.
Living with urticaria
Tips for acute urticaria
- Avoid suspected triggers if possible.
- For temporary relief of symptoms, ask your doctor or pharmacist about taking antihistamines.
- A comprehensive diagnosis and allergy tests are usually not necessary if the symptoms only last for a period of less than six weeks. If the symptoms last longer, you should see a doctor.
Tips for chronic urticaria
- If the cause or trigger is unknown, it is a good idea to keep an urticaria calendar or an urticaria diary. This will help you and your doctor identify the possible cause.
- For more practical tips, please go to the Tips and Tricks section of the Urticaria Network website.
Prof. Dr. med. Dr. h. c. T. Zuberbier
Last changes made: March 2017