What Are Hives? What Is Urticaria? What Causes Hives?

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Main Category: Dermatology
Article Date: 13 Jul 2009 - 1:00 PDT

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Hives are also known as urticaria, welts, wheals, or nettle rash. It is a red, raised, itchy skin rash that is sometimes triggered by something that produces an allergic reaction - an allergen. When there is an allergic reaction the body releases a protein called histamine. When histamine is released our capillaries (tiny blood vessels) leak fluid. The fluid accumulates in the skin and causes a rash.

According to Medilexicon's medical dictionary, urticaria is "An eruption of itching wheals, colloquially called hives, usually of systemic origin; it may be due to a state of hypersensitivity to foods or drugs, focus of infection, physical agents (heat, cold, light, friction), or psychic stimuli."

Urticaria can be triggered by:

• Certain foods.


• Insect bites and stings.


• Contact with an irritant, such as nettles, chemicals or latex.


• Certain medications - such as NSAIDs (nonsteroidal anti-inflammatory drugs), used to treat pain, ACE inhibitors, used to treat hypertension (high blood pressure).


• Extremes of temperatures.


• Sunlight.


• Water on the skin.

Experts say that in about half of all cases of urticaria the cause is never found.

According to the National Health Service (NHS), UK, about 1 in every 6 people will suffer from urticaria at some time in their life. Children and women are more commonly affected than adult men. Urticaria is not contagious - you cannot pass it on to another person.

Acute urticaria or Acute hives

When symptoms last less than 6 weeks it is called acute urticaria. This is by far the most common type. 25% of people with acute urticaria also have angioedema - swelling in the deeper layers of skin.

Chronic urticaria or Chronic hives

If symptoms of urticaria continue for more than six weeks it is called chronic urticaria. Dermatologists say that about 1 in every 1,000 people suffers from chronic urticaria. Experts are not completely sure what the causes of chronic urticaria are. However, most agree that it is closely linked with our immune system. In some cases, chronic hives may be related to an underlying autoimmune disorder, such as thyroid disease or lupus. 50% of people with chronic urticaria also have angioedema.

Angioedema is similar to urticaria, but occurs deeper inside the skin. The swelling causes a burning sensation and typically occurs on the face and neck, fingers, toes, and in the genitals of males.

What are the symptoms of urticaria (hives)?

Swellings, known as wheals, appear on the skin as a rash. They are usually pink or red and have an oval or round shape, and range from a few millimeters in diameter to a several inches. They can be extremely itchy. The wheals may be surrounded by a red flare.

The wheals usually occur in batches, and frequently appear on the face or the extremities (arms, hands, fingers, legs, feet, and toes).

In most cases a welt will disappear after a few hours, but me be replaced by new ones. They can appear on just one part of the body, or several parts.

In the majority of cases symptoms are present for no more than 8 to 12 hours, and rarely continue for more than 24 hours. However, with some patients the problems may continue for quite a few days, and even several months.

Anaphylaxis

Anaphylaxis is a severe allergic reaction. The patient can have serious breathing difficulties, and can even lose consciousness and die if not treated quickly. The allergic reaction may involve the whole body. Anaphylaxis is a medical emergency. If somebody has urticaria it is important to be alert for further symptoms which could indicate an anaphylaxis reaction. Anybody who experiences the symptoms listed below should call the emergency services immediately:

• Nausea and vomiting.
• Swelling of the lining of the mouth, tongue, lips and throat; causing breathing difficulty.
• Cold and clammy skin.
• Rapid heartbeat.
• Feeling faint or lightheaded.
• An unexpectedly abrupt feeling of intense anxiety.

What are the causes of urticaria (hives)?

Experts say that urticaria occurs when the body releases histamine and other chemicals from under the surface of the skin. The histamine and chemicals cause inflammation and fluid to accumulate under the skin, causing wheals. In about 50% of all acute urticaria cases the trigger is unknown. The following are examples of some known triggers:

• Medications - including NSAIDs, such as aspirin and antibiotics.


• Foods - several different types of foods have been known to trigger urticaria. The most common ones are nuts, chocolate, some citrus fruits, shellfish, food additives, eggs, and wheat products.


• Infections - including influenza, the common cold, glandular fever and hepatitis B.


• War zones - Throughout the history of warfare, dermatologic diseases have been responsible for troop morbidity, poor morale and combat ineffectiveness . Dermatitis, benign moles, hives and cancerous skin lesions are among the most common diagnoses among military personnel who were evacuated from combat zones for ill-defined dermatologic diseases, a study revealed.


• Intestinal parasites.


• Extremes of temperature.


• Some pets.


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• Dust mites.


• Floods and hurricanes - skin diseases/disorders are commonly found among people after floods and hurricanes, including urticaria. Construction workers who help repair damaged structures are also more likely to suffer from skin diseases/disorders, a study revealed.


• Sunlight exposure (less common).


• Latex.


• Nettles.


• Some plants.


• Insect bites.


• Some chemicals.


• Chronic illness - such as thyroid disease or lupus.

Chronic urticaria (long term urticaria), on the other hand, is hardly ever caused by these triggers. Chronic urticaria generally starts as an autoimmune response in which certain cells (mast cells) cause the release of histamine and various chemicals to be released under the skin, causing tiny blood vessels to leak, which results in swelling and wheals. Experts do not know why this happens.

How is urticaria diagnosed?

Acute urticaria diagnosis

A GP (general practitioner, primary care physician) can easily diagnose acute urticaria by examining the rash on the skin. The doctor will attempt to find out what the trigger was, as this may help the patient prevent recurrences. Typically, the doctor will ask the patient the following questions:

• When the episode began.


• Where the episode began.


• Whether the patient lives or works in a place where potential triggers may exist, such as latex gloves, chemicals, or animals.


• What medications the patient has been taking, including herbal supplements.


• The patient's medical history.


• Whether the patient had been bitten by an insect.


• Whether any close relatives also have/had urticaria.

In half of all cases the doctor and patient will never find out what the trigger was. However, most cases will resolve themselves within a few days and never recur.

If a doctor believes there may be a trigger which is causing an allergic reaction the patient may be referred to an allergy clinic (UK). Allergy clinics test the patient's blood and skin to find out whether there is an allergy to specific substances, such as chemicals, dust mites, or some food.

Chronic urticaria diagnosis

If the urticaria continues for more than six weeks the likelihood of there being some external trigger is extremely small; which is why allergy tests are not recommended. Nevertheless, the GP will be interested in factors which may exacerbate the existing urticaria, such as alcohol, caffeine intake, mental health (stress), etc. If there are any underlying causes for the chronic urticaria the doctor may order the following tests:

• A blood test to find out whether the patient is suffering from anemia.


• A stool sample to check for parasites.


• ESR (erythrocyte sedimentation rate) test - this can identify problems with the patient's immune system.


• Thyroid function test - this identifies either hyperthyroidism (overactive thyroid) or hypothyroidism (underactive thyroid).


• Liver function tests - these can identify whether the patient has any liver problems.

What is the treatment for urticaria?

Allergic skin disorders, such as urticaria and atopic dermatitis, can cause much discomfort, have an impact on quality of life, and can sometimes cause serious complications. Like other allergic conditions, these disorders can often be effectively treated, according to the American College of Allergy, Asthma and Immunology.

Acute urticaria treatment

Generally, no treatment is needed for acute urticaria because symptoms are usually mild and the condition is short-lived and rarely recurs.

• Antihistamines - However, if symptoms are more severe, or if the condition persists the patient may be given antihistamines. Antihistamines block the effects of histamines and reduce the rash and stop the itching.
  
  Current antihistamines do not make most patients drowsy. Unfortunately, some patients may be affected and should check how they react to the antihistamine before operating heavy machinery or driving a car. Antihistamines often cause drowsiness if the patient has alcohol in his/her system.
  
  Some patients may benefit from antihistamines that do cause drowsiness, especially if the itchiness is causing sleep problems.
  
  Pregnant women should not take antihistamines, unless the GP prescribes it. Very occasionally GPs may prescribe an antihistamine called chlorphenamine for pregnant women if it is felt the benefits are greater than the risks. In the UK thousands of pregnant women have taken chlorphenamine, and so far there have been no reports of any harmful effects to the unborn baby.


• Corticosteroids - If symptoms are very severe the doctor may prescribe a short course of high-dose oral corticosteroids, which suppress the immune system which usually results in either eliminating or reducing the symptoms of urticaria. Corticosteroids should not be taken for more than 5 days. The longer a patient takes Corticosteroids the greater his risks are of getting an infection.

Chronic urticaria treatment

Patients with chronic urticaria will have treatment which is aimed at controlling symptoms and avoiding triggers that may make them worse.

Patients who have chronic urticaria and angioedema should be referred to an immunologist, an allergist or a dermatologist (skin specialist doctor). Angioedema can cause breathing difficulties which can potentially cause serious problems.

Patients who only have chronic urticaria and nothing else, but whose symptoms are still severe should also be referred to a specialist.

• Antihistamines - antihistamines can treat the symptoms of chronic urticaria. If symptoms are causing sleep problems the patient may benefit from also taking the antihistamines that cause drowsiness.


• Menthol cream - this has been shown to be a useful alternative or addition to antihistamines for patients with itchiness.


• Corticosteroids - these may be prescribed for chronic urticaria patients whose symptoms are more severe.


• Avoiding triggers - as triggers can make the existing urticaria worse, it is important for the patient to identify these triggers and avoid them. Remember, that with chronic urticaria the triggers do not cause the condition, but they can make it worse. The patient may have to abstain from consuming alcohol, or cut down consumption. He/she may have to avoid certain medications as well. Avoiding stress may help - however, this may not be easy, especially if the symptoms are affecting the patient's quality of life. Some soaps may be making symptoms worse, as well as skin creams and detergents.


• Meditation or hypnosis - relaxation techniques, such as medication or hypnosis have been found to help reduce symptoms and levels of stress in severely affected patients.


• Diet - many patients swear that certain foods make their symptoms worse. This is a controversial subject in which experts seem to have different opinions. The following foods are known to trigger histamine production - spinach, fish, yoghurt, fish, tomato, processed, meats, chocolate, and strawberries.

What are the complications of urticaria?

Acute urticaria complications

Approximately one quarter of all patients with acute urticaria also develop acute angioedema, which should resolve itself within about three days. Patients who have breathing problems should call the emergency services immediately. Angioedema is treated with antihistamines and oral corticosteroids.

Chronic urticaria complications

About half of all chronic urticaria patients will get better within 3 to 5 years. One quarter of all patients will continue having symptoms for over 10 years. As with any chronic condition, the patient can become frustrated and distressed. Approximately 15% of chronic urticaria patients report feelings of depression. Patients with symptoms of depression should inform their doctor. Depression is treatable.

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today