Hives (urticaria): Triggers and treatment
Urticaria, commonly known as hives, is a condition where red, raised patches (sometimes called weals or welts) appear on the skin, often accompanied by an unpleasant itchiness. Urticaria is one of the most common skin rashes and affects one in every four to five people at some point in their life. The first World Urticaria Day was held on 1 October 2014 with the objective of raising awareness of the symptoms around the world. Read on to find out more about the various forms, potential triggers and the treatments available for hives.
Symptoms of hives
Hives is a very common skin condition that can take a range of different forms. Around one in every four to five adults will experience an outbreak of hives at least once in their life. The primary symptom of urticaria is a rash of red, raised patches. The skin rash is different for each form of the condition and may be isolated, widespread or appear across the entire body. The size of the rash also differs from one patient to the next: in some cases, the rash comprises spots of just a few millimetres across, while other people develop patches of several centimetres in diameter. The rash is accompanied by extreme itchiness. A burning sensation and extreme sensitivity are also possible in the affected areas. Some patients also develop swollen skin, known as angioedema, in their face and extremities.
Forms of hives
A basic distinction is made between two forms of the condition: acute and chronic. The term acute urticaria denotes symptoms or complaints that appear once for a few days or weeks before receding gradually of their own accord. For the most part, the symptoms of this form of the condition can be managed quite effectively. Chronic urticaria, on the other hand, is a considerably more complex skin condition that is also more difficult to treat. Chronic urticaria is diagnosed when the symptoms persist for longer than six weeks. While the individual raised patches may not remain in one place for more than 24 hours, they may reappear on other parts of the body. Chronic urticaria is further divided into chronic inducible urticaria (where a trigger can be identified) and chronic spontaneous urticaria (where the trigger remains unclear).
Trigger factors of hives (urticaria)
Depending on the form and sub-form of the condition, hives can be triggered and exacerbated by various internal and external factors:
- Acute urticaria: Though it is not always the case, acute urticaria is very often triggered by an allergy. The potential causes of acute urticaria include food allergies and intolerances, infections, medication intolerances (such as an intolerance to certain antibiotics, such as penicillin, sulfonamide, etc.), antipyretic painkillers (e.g. ibuprofen, diclofenac, etc.) and medication for high blood pressure or heart conditions (e.g. beta blockers, diuretics, etc.).
- Chronic urticaria: In contrast to acute urticaria, chronic urticaria (both inducible and spontaneous forms) is almost never caused by an allergy.
- Chronic inducible urticaria (physical urticaria): Chronic inducible urticaria is usually triggered by physical stimuli and – depending on the physical trigger – can be divided into:
- Cold urticaria: Cold urticaria is one of the most common forms of physical urticaria. In this form, the typical symptoms of the condition are caused by contact with cold (e.g. cold air, cold water, cold items, sweat, etc.). The skin alterations appear on the parts of the body that come into contact with the cold, which is why uncovered areas of skin such as the hands and face are usually affected.
- Heat-induced urticaria: Heat-induced urticaria is less common than other forms of the condition. The cause of heat-induced urticaria is localised heat (e.g. taking a hot shower or bath, using a hairdryer, eating hot food, etc.).
- Solar urticaria: The trigger for solar urticaria is visible light or ultraviolet radiation. This form is most common among young adults, with women on average more likely to suffer from it than men. Sunlight in particular causes the characteristic raised red patches to appear on the skin, along with an unpleasant itchiness. However, the mechanism that connects light radiation to a breakout of hives is not yet fully understood.
- Pressure urticaria: Heat-induced urticaria is less common than other forms of the condition. Pressure urticaria denotes a condition where the symptoms are triggered by applying pressure to skin. Pressing on the skin or impacting on something can cause swelling which, in many cases, can also be painful.
- Dermatographia: The trigger of dermatographia (also known as dermatographic urticaria) is so-called shear forces which can be caused, for example, through rubbing, chafing or scratching. The reaction develops on the skin shortly after the skin has been irritated. However, only the areas of skin which have been rubbed, chafed or scratched are affected. For some patients, even lightly stroking the skin is enough to cause an outbreak of raised patches; other patients might only develop symptoms after more firm or intense scratching or rubbing.
All sub-forms of chronic individual urticaria can appear either on their own or together with other sub-forms.
- Chronic spontaneous urticaria: The exact triggers of chronic spontaneous urticaria remain unclear. It is generally assumed that the possible causes are infections, autoimmunity and reactions to intolerances (e.g. to medications, food additives and preservatives). As its name suggests, chronic spontaneous urticaria is characterised by its spontaneous onset. The red, raised patches appear repeatedly for a period of more than six weeks.
Underlying causes of hives
While the triggers of the individual forms of urticaria may vary, the processes that ultimately lead to skin alterations and complaints are the same for every form and sub-form. Following specific irritation, the body’s mast cells (mastocytes) emit various biochemical messengers, including histamine.
Mast cells are the cells in our immune systems that are crucial, among other things, in defending the body against pathogens and healing wounds. In addition, mast cells also play an important role when it comes to allergies, primarily through immediate allergic reactions. As soon as an irritant activates the mast cells, the cells begin to release specific messengers into the interstitium (the spaces between cells, tissue or organs).
Histamine is a so-called tissue hormone. It appears almost everywhere in the body, including in the skin. Histamine plays in important role in numerous physiological processes. When histamine is released, it causes blood vessels to dilate and thereby allow fluid to permeate tissue. This is what causes the redness and raised patches on the skin. At the same time, histamine causes the itchy sensation at nerve endings.
Diagnosis of hives
A doctor usually recognises the red, raised patches at first sight. If the patient visits a doctor at a point in time when no skin rash is present, the patient providing a detailed description of their complaints and symptoms can be decisive in diagnosing the condition. In any case, a comprehensive discussion of the patient’s medical history is important. As well as providing essential information, it is a valuable diagnostic tool in identifying or ruling out potential triggers (cold, heat, light, pressure, shear forces, medications, foods, infections, etc.) at an early stage and also makes it possible to determine whether the patient has an acute or chronic form of urticaria.
Important differential diagnosis in the event the case of suspected urticaria include urticaria vasculitis and autoinflammatory syndromes (cryopyrin-associated periodic syndrome, Schnitzler syndrome) – these conditions present with similar symptoms to chronic spontaneous urticaria and must be excluded before treatment can begin.
After discussing the patient’s medical history, the doctor may conduct a range of examinations and tests in order to identify the cause of the hives. The tests detailed below may not necessarily be used as part of the diagnostic process. Based on the symptoms observed and the information gleaned from the patient’s medical history, the doctor will decide what tests are required in the respective case.
- Physical challenge tests: Physical challenge testing can help to identify or exclude a trigger of urticaria caused by physical irritation. It can be used to diagnose pressure urticaria or dermatographia, as the doctor strokes or applies gentle pressure to the skin using a tongue depressor or another suitable medical instrument. In the case of suspected solar urticaria, light testing is carried out in which the skin is radiated with light of varying wavelengths. Cold urticaria can be diagnosed with the help of ice cubes or special temperature-controlled baths.
- Allergy tests: Allergy testing – such as skin prick testing – is ordered to identify allergies.
- Stool sample: Microbiological analysis of a stool sample can provide indications of potential parasites.
- Other laboratory tests: Other laboratory testing includes determining signs of inflammation in the blood, determining the presence of antibodies against specific viruses and analysing the patient’s urine for indications of inflammation and other parameters.
- Elimination diet: In an elimination diet, the patients follows a special nutritional plan in which they must avoid foodstuffs associated with hives (foods with high histamine content, high levels of additives (flavourings, colouring agents and preservatives) and allergens).
- Ultrasound scans of the abdominal organs and lymph nodes
- Further testing as required (examinations of the ear, nose and threat (ENT), the gastrointestinal tract, psychosocial triggers, etc.). Treatment for hives The treatment prescribed for hives is determined by the form of the condition and the patient’s symptoms.
- Acute urticaria usually recedes on its own within a few days or weeks, which is why symptomatic treatment is prescribed. Patients are given antihistamines to combat the red, raised patches and itchiness; if necessary, they may be prescribed other medications to treat specific symptoms (difficulty swallowing, angioedema, etc.). If triggers have been identified, it is important that the patient avoids them as far as possible. If the symptoms are caused by taking certain medications, these should be replaced by alternatives following consultation with a doctor.
- A three-stage course of therapy is available to treat chronic spontaneous urticaria. First of all, patients are treated with a selected antihistamine. If the symptoms improve in the fortnight that follows, the dosage is then increased (up to four times the original dosage). If altering the dosage and trying another antihistamine both fail to remove the patient’s symptoms within two months, treatment with an immunologically active protein is then prescribed.
Patients with a severe form of chronic spontaneous urticaria are advised to carry an emergency kit around with them so they can manage a serious onset if necessary. The emergency kit contains at least one antihistamine and a fast-acting cortisone preparation.
- Treatment of chronic inducible urticaria should target the cause of an outbreak – that is to say, patients should avoid the diagnosed triggers as far as possible. While it may not always be possible to avoid the triggers in every case, the patient should at least avoid direct, intentional contact with them (e.g. by jumping into cold water or eating very cold foods if they have cold urticaria; by exposing their skin to direct sunlight without a high-factor sun lotion if they have solar urticaria, etc.). Otherwise, this can result in dangerous cardiovascular responses and symptoms of shock.
Ointments and creams containing witch hazel or calendula may help to relieve the itchiness. These plants have anti-inflammatory and vasoconstrictive properties. A vinegar compress may also reduce the urge to itch.
Hives (urticaria) is a very common skin condition.
Primary symptom: Skin alterations in the form of red, raised patches
The red, raised patches may range from a few millimetres to a several centimetres in diameter, and may be isolated, extensive or across the entire body.
Other possible symptoms: Itchiness, burning sensation, soreness sensitivity of the skin, angioedema and difficulty swallowing, difficulty breathing, tiredness and lethargy Forms: Acute urticaria (duration: less than six weeks) and chronic urticaria (duration: longer than six weeks).
Sub-forms of chronic urticaria: Chronic inducible urticaria and chronic spontaneous urticaria Potential triggers of chronic inducible urticaria: Cold (cold urticaria), warmth (heat-induced urticaria), light (solar urticaria), pressure (pressure urticaria), shearing forces such as rubbing, chafing or scratching (dermatographia) and others.
Diagnosis: Discussion of medical history, skin examination and further testing as required (e.g. physical challenge tests, allergy testing, laboratory tests, elimination diet, etc.) Treatment: Medication containing antihistamines The chronic form of urticaria is treated in a three-stage treatment plan
Other treatments: Avoiding known triggers, antipruritic creams and ointments
Autor: Katharina Miedzinska, MSc