What is Urticaria?
Urticaria is a complex skin hypersensitivity reaction. Itching usually occurs. It is part of the skin diseases with major incidence worldwide. The statistical probability of having hives throughout life is around 20%. Urticaria is not contagious.
The term urticaria derives from Latin urtica, which means nettle. Urticaria is characterized by symptoms that are comparable to those that appear after having contact with nettles: a rash of the rash type that produces a lot of pruritus (itching). In almost half of the cases of urticaria there is also an extensive inflammation of the tissue of the deep dermis and of the hypodermis or certain areas of the basal membranes of the mucous membranes. This results in a condition called angioedema.
Urticaria can appear at any age, although certain forms are more or less common depending on the age group. Acute urticaria mainly affects adolescents and young adults. Middle-aged women mainly suffer from chronic urticaria.
When a hives does not last more than six weeks, it is considered an acute urticaria. Urticaria usually decreases until its resolution in time, from one to two weeks on average. Skin often begins to regain its normal appearance in 24 hours, as well as the inflammation, redness and itching disappears.
1 in 10 cases, acute urticaria becomes chronic urticaria. The dermatologist diagnoses chronic urticaria when disease manifests itself for more than six weeks. As a rule, chronic urticaria can be prolonged for up to three and five years. According tothe severity level of chronic urticaria, rashes and inflammation can even limit the professional and personal life of the affected person.
Urticaria can become dangerous to health when the mucous membranes of the tongue and larynx are inflamed. It can also lead to a serious allergic reaction to the immune system, called anaphylaxis. Because of this, urticaria can cause a state of shock (anaphylactic shock) which can lead to cardiorespiratory arrest. However, both inflammation of the mucous membranes of the tongue and larynx are extremely rare and respond well to treatments.
What is the definition of urticaria?
The term urticaria describes a complex group of diseases in which two basic forms are distinguished according to the duration of the condition: ‘’acute urticaria and chronic urticaria’’. Regardless of whether it is an acute urticaria or a chronic urticaria, there are multiple classifications of urticaria (depending on the cause or triggering mechanism). The common characteristic of all of them is the skin reaction that in the urticaria manifests as itchy rashes in the form of hives.
These hives are well delimited and have an uneven surface compared to unaffected skin. The skin is red, itchy and may even scab. Nearly half of the cases are accompanied by inflammation of the tissue of the deep dermis and hypodermis (the deepest layer of the three that make up the skin) or of certain areas of the basement membranes that may occur in different locations of the body. Rarely, urticaria results in an extreme and anomalous reaction of hypersensitivity to the immune system, called anaphylaxis, which can be fatal if left untreated.
What causes urticaria?
Urticaria can be caused by numerous causes. Depending on the cause, different classifications of urticaria are also done and two or more forms may be present in the same patient. Thus, in an attempt to systematize, we can divide hives into several categories according to the causes:
Urticaria of exogenous causes
Urticaria is caused by external factors. Within this, classification are the following types:
Physical urticaria: Triggers are irritations caused by physical mechanisms such as temperature (eg cold) or mechanical irritations, such as pressure on a skin area.
Allergic and pseudoallergic urticaria: Triggers are mainly medicines or foods.
Secondary or symptomatic urticaria
Triggers of this type of urticaria are acute, chronic infections and even undiagnosed infections or also autoimmune diseases. Urticaria is considered to be a symptom of another pathology.
The cause of this hives is unknown. Only 20% of chronic urticaria can identify a possible cause. Different types of urticaria may also present combined in circumstances where individual triggers may intensify one another.
Urticaria due to exogenous causes
Physical urticaria develops due to irritations caused by pressure, temperature, certain forms of radiation and, in rare cases, by contact with water. This urticaria depends on the intensity and duration of irritation caused by the agent in question (for example, in the case of cold irritation). As a rule, urticaria appears as a contact in the area of the skin where irritation has occurred. However, physical urticaria can also extend beyond the contact zone and cover a wide area. This form of urticaria develops frequently as a chronic type.
Factitious urticaria or dermographism develops by the action of a force, for example, scratches, rubbing, rubbing or pressure (for example, by a belt). The skin reacts in a matter of minutes with the formation of hives and pruritus. A special form of factitious urticaria is pressure urticaria, which originates from vertical pressure or from vibration. Pressure urticaria may present with a delay of several hours.
In delayed factitious urticaria, the characteristic rash appears with a delay of at least 30 minutes (usually several hours) after irritation and tends to disappear within 24-48 hours.
Cholinergic urticaria can be caused by an increase in body temperature. Chronic urticaria is more frequent and multiple physical agents are capable to cause it, especially changes in temperature and exercise, psychological factors such as stress or anxiety situations and some situations that can trigger or exacerbate hives. Hence, cholinergic urticaria is also called urticaria due to sweat or exercise urticaria, since body temperature increases precisely when practicing sport, but it can also appear when you have a fever or are suffering from psychic stress or when bathing in hot water.
More types of urticaria are cold urticaria, solar urticaria and aquagenic urticaria (water urticaria). Contact with ice, cold metals or cold water triggers is a form of urticaria called cold urticaria. It manifests itself both locally and generalized throughout the body. Cold urticaria can be fatal more often than other types, because it is more likely to result in an extreme reaction of the immune system (anaphylaxis). In extreme cases, the mucous membranes may become inflamed when drinking cold drinks. It would be a case of cold urticaria. Taking into account all cases of urticaria, those that are triggered by the cold are relatively rare.
Like cold urticaria, solar urticaria is also considered a rare form of urticaria. Both normal daylight and UVA radiation can trigger this form of urticaria. It is an immediate response in the first 5 minutes after sun exposure. The first symptom is pruritus, and then erythema is usually maintained for 2-3 hours.
Equally rare is aquagenic urticaria (water urticaria). This is a type of urticaria secondary to contact with water regardless of the temperature at which it is found.
Allergic urticaria can develop because of certain medications, such as penicillin and other antibiotics, but also by vaccines and blood products. Other possible triggers include contact with insect venom. The variety of causes that can cause allergic urticaria comprises practically the whole range of foods, from fruits and vegetables to animal products, from cereals to dairy products.
The symptoms of a pseudoallergic urticaria are similar to those of an allergic urticaria. Unlike allergic urticaria, pseudoallergic urticaria can manifest even hours after contact.
Symptomatic or secondary urticaria
Symptomatic or secondary urticaria is considered as symptoms of another pathology. The causes are due to acute or chronic infections of the gastrointestinal tract or upper respiratory tract, which are often yet diagnosed at the time of onset of urticaria. Possible triggers of endogenous urticaria are infections by the bacterial pathogen helicobacter pylori in the gastrointestinal tract, by certain intestinal parasites such as worms or by a viral infection such as hepatitis A or hepatitis B.
Hormonal changes which are derived from the thyroid diseases or of a pregnancy can be the cause of an endogenous hives. Also, certain diseases that are manifested by the alteration of the body’s own immune system autoimmune diseases can cause endogenous urticaria. Examples include autoimmune diseases such as systemic lupus erythematosus which affects the skin, kidneys and joints. Rarely, the causes of endogenous urticaria are due to chronic diseases such as cancer. The evolution of an endogenous urticaria depends on the triggers, as well as on the evolution of the infection that originated it. In this sense, if the infection is acute, urticaria evolves acutely, whereas if it is a chronic infection, urticaria usually manifests in a chronic form.
Urticaria in children
Urticaria that occurs in children is often the consequence of pseudoallergic reactions of the body whose symptoms resemble an allergic reaction. However, unlike a true allergic reaction, characteristic immune reactions of allergy are not manifested. The causes of urticaria in a child are as varied as in adults: they range from allergens to viral infections, colonies of fungi and worms in the intestine to certain autoimmune diseases and cancerous diseases. Another cause that can trigger urticaria in children are physical stimuli such as cold or solar radiation.
What are the symptoms of urticaria?
Urticaria is characterized by two symptoms and a third that appears in half of the cases:
- Itching or pruritus.
- Rash in the form of rash or hives.
- Inflammation of the tissue of the deep dermis and hypodermis (angioedema)
Urticaria usually begins with itching in one area of the body. The characteristic itching of urticaria differs from other itching (for example, eczema) in which the person tends to rub more or to push the affected area than to scratch. As it develops a reddish rash forms in the form of hives or hives that reminds of the irritations of the skin after having been in contact with nettles. The rash is clearly delimited and presents an uneven surface compared to unaffected skin. Its color is reddish and whitened when it is pressed, for example, with a glass (glasspressure).
Angioedema may be present in about half of all cases of urticaria. This can accompany the rest of symptoms (itch and hives) or manifest exclusively.
An angioedema is formed mainly in the lips and in the area around the eye or periorbital. In isolated cases, it affects the hands, feet or genitalia. When it affects mucous membranes of larynx or area around the larynx or the tongue or the digestive mucosa may become inflamed.
An angioedema usually occurs as a result of acute urticaria and warns of the presence of a hypersensitivity reaction in the body (anaphylaxis). It can lead to inflammation of the tongue, larynx, or the area around the larynx. In addition, airways may narrow with spasmodic constrictions and trigger a bronchospasm crisis.
Angioedema may also be accompanied by gastrointestinal symptoms, such as diarrhea and vomiting, as well as fever (urticaria fever).
Anaphylactic shock may be manifested when anaphylaxis, which occurs in the course of an urticaria. Anaphylactic shock is a medical emergency like anaphylaxis which requires urgent medical attention. Failure to treat your symptoms can lead to cardiac and respiratory arrest. Anaphylactic shock is characterized by the following symptoms:
- Significant decrease in tension (hypotension)
- Significant decrease in cardiac output
- Respiratory distress due to constriction of the bronchial musculature (bronchospasm)
- Extensive tissue inflammation of the hypodermis (angioedema)
- Inflammation of the tongue and larynx
How is urticaria diagnosed?
In order to establish the diagnosis, the first thing to determine is if we have a picture of urticaria and not before another type of rash.
Urticaria has numerous triggers. In the diagnosis of urticaria, doctor focuses mainly on two objectives regardless of the type of urticaria, which are: on the one hand, to find out the causes of urticaria by asking a series of specific questions to the patient and, on the other hand, symptoms that accompany with the condition.
In acute and recurrent urticaria, the most important diagnostic element is the clinical history. Through its frequency and severity of the outbreaks, the natural evolution (spontaneous or after treatment), as well as a first approximation to the triggers are collected.
For the diagnosis of urticaria, the doctor asks a series of questions about the previous history, such as when he has hives, how long and how often the rash has occurred, if he has noticed changes in the rash. During the day and what was the treatment of previous episodes of urticaria. In addition, he tries to find connections with certain events: does hives occur recurrently, mainly at the weekend, on vacation or when traveling to foreign countries? Are there any previous illnesses? Does the family have frequent urticaria? He will also question how daily routine and lifestyle of the patient, the type of work he performs, hobbies and possible stressors are structured. And if you have toxic habits like tobacco and alcohol.
The diagnosis of the disease itself is evident by simple examination (lesions, erythematous and pruriginous), but it is simple even if the patient does not present lesions at the moment of the consultation, since the description of the symptoms does not offer diagnostic doubts. In the case of angioedema, it may be necessary to perform differential diagnosis with edema of another etiology.
As a general rule to establish a diagnosis of urticaria, the following laboratory tests are requested:
- Erythrocyte sedimentation rate
- Immunological study: IgG, IgM, IgA, IgE, specific IgE (CAP; RAST)
- Complement study: C3, C4, CH50, CH 1 inhibitor
- Thyroid function study and antibody titers
- Autoimmunity study, rheumatoid factor
- Virus serologies, VDRL, cryoglobulins
- Urine or stool analysis. Parasitological study in feces
- Specific tests with food
- ice cube
- light exposure
- vibratory agitator
- intradermal methacholine
- aquagenic exposure
If there is suspicion that the triggers are physical, such as pressure, cold or heat during the diagnosis of urticaria, doctor performs what is called a provocation test. The provocation test consists in provoking the irritation of a certain area of the skin applying the trigger under suspicion, this is assessing the reaction of the skin to compression, cold irritation or physical exertion.
If it is necessary, allergy tests such as prick test can be performed to determine the diagnosis of urticaria, which allow the identification of certain allergens as triggers for urticaria.
The treatment of urticaria is based mainly on three grounds:
- Avoid triggers, for example, by eliminating foods that cause hives or treating the infections that cause it.
- Keep in mind that the active principles of antihistamines can inhibit the action of histamine that triggers urticaria.
- Follow brief treatment with immunosuppressive active substances, for example, corticosteroids or cyclosporine. These stabilize immune cells actively involved in the onset of urticaria, mast cells, and reduce the secretion of the inflammatory mediator called histamine.
Location of the cause
The main objective of any treatment for urticaria is to locate the causes of the condition and to avoid them. Triggers can be multiple and comprise from a wide variety of foods or medications to infections and physical irritations, for example, by cold or pressure. There is often more than one cause responsible for the onset of hives. And often the cause can not be determined despite all the diagnostic tests performed. In this regard, in urticaria and its treatment attempts to locate factors that may not trigger the condition, but do intensify. Therefore, getting the treatment of acute urticaria and especially chronic chronic urticaria successful is a long and difficult process.
Treatment of urticaria symptoms
The treatment of urticaria begins mainly with the determination of the causes. This process can be extended over a long period of time. The doctor will begin treatment of urticaria by treating symptoms, usually with medications with active ingredients of the class of antihistamines antiH1. This class of drugs have been used for the treatment of urticaria since the 50’s, date from which they have been continuously evolving. The new generation of anti-H1 antihistamines currently used for the treatment of urticaria is better tolerated than the previous ones. Current antihistamines have mostly suppressed the side effect of increasing drowsiness that previously appeared with the treatment of urticaria.
If the treatment of urticaria with antihistamines does not offer satisfactory effects, even after increasing the dose, the doctor will advise the ingestion of so-called corticosteroids in the next phase of treatment. These stabilize mast cells, which are the cells of the immune system that are actively involved in the onset of urticaria, and thus achieve less secretion of histamine, which is the inflammatory mediator. However, corticosteroids should only be taken for short periods, as prolonged treatment with these drugs has side effects that are detrimental to health. That is why corticosteroids are especially used in cases of acute urticaria as well as when a spontaneous worsening of chronic urticaria occurs.
Antihistamines and cyclosporine
In some cases, the doctor treats urticaria with a combination of antihistamines antiH1 and cyclosporine. The active cyclosporin acts with regulatory effects on the immune system reducing the secretion of histamine, which is the inflammatory mediator that actively contributes to the onset of urticaria. Cyclosporine treatment is used exclusively in patients suffering from severe recurrent urticaria despite being treated with antihistamines as a single treatment.
Treatment of hives with phototherapy
The treatment of urticaria with medication can also be supplemented with phototherapy to relieve the symptoms of the condition. Of course, only when it is a hives that has not been caused by light. Phototherapy is sometimes used in cases of idiopathic chronic urticaria.
Urticaria in children
In the treatment of urticaria in children, the pediatrician also prescribes antihistamines antiH1. However, anti-H1 first-generation antihistamines (deschlorpheniramine and hydroxyzine) are often used in these cases, whose side effects are known better than in the new anti-H1 antihistamines. Anti-H1 antihistamines reduce the secretion of histamine, which is the inflammatory mediator that actively participates in the onset of urticaria.
Urticaria in pregnancy
Intake of medications for the treatment of urticaria (eg anti-H1 antihistamines) should be avoided if possible in pregnant women especially during the first trimester of pregnancy. To date there is no systematic study about the risks that most of the medications used to treat hives may have on pregnancy. Therefore, it is up to the physician to agree with the patient after weighing pros and cons whether it is appropriate to treat hives with medications or to give up treatment and instead assume a possible increased risk for mother and child.