Urticaria: An Allergic Skin Reaction

Posted by Pragati Priya on Sun, Apr 14, 2024  
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Introduction:
Urticaria is also referred to as “Hives”. These are allergic skin reactions characterized by itchy, raised, reddish rashes on skin. Urticaria is generally caused by contact with some allergens. These rashes vary in size and location from person to person. It may be present as a small spot in some individuals, while it may present as a larger lesion in other individuals.
Causes:
Urticaria is a very common skin infection. The exact cause of urticaria is still not established but it is believed that it could be due to multiple factors. Some of the possible causes are as follows:

 

  • Allergens: Several substances when taken cause allergic reactions in the body. These are called allergens. In response to allergies, a protein called Histamine is released in the body. Histamine in turn causes the capillaries to expand making the skin inflamed and itchy.

  • Medicines: Some antibiotics, non steroidal inflammatory drugs (NSAIDs), angiotensin converting enzyme (ACE) inhibitor can cause allergic reactions in some individuals.

  • Latex allergy: This is common in healthcare professionals who use latex gloves during practice. Hence, the use of latex free gloves should be encouraged in such cases.

  • Insect: Papular urticaria is caused by insect bite. It is a hypersensitivity reaction. It can occur by insect bites such as caterpillars, moths, mosquitoes, beetles, etc.

  • Blood transfusion: This is the most common side effect of blood transfusion. Some allergens in the donor blood can cause urticaria to the recipient.

  • Pressure: This can be caused due to putting pressure in an area for a long time such as wearing tight shoes, tight clothes, etc. It is a rare case.

  • Beauty products like skin care or hair care products are often likely to cause urticaria in some individuals.

 

Symptoms:

 

  • Raised skin lesions

  • Reddish color rashes (harder to see on dark skin)

  • Itchy rashes (itchiness worsen in night)

  • Burning sensation

  • Lesions are round, oval or worm- shaped

  • Localized or generalized rashes

  • Varying size of skin rashes

  • These rashes might disappear and reappear after sometime

  • Angioedema in severe cases.

 

Angioedema:


Angioedema can occur as a consequence of urticaria. It is a hypersensitivity reaction that affects the subcutaneous tissue i.e. the inner layer of the skin. This condition is characterized by fluid build up in the tissues. Angioedema is a non pitting edema which means the swollen surface when pitted using fingers, pits are not formed or if formed they don't return to normal skin level again.

 

It was first studied by Quincke in 1882

 

Symptoms of angioedema include swelling around the eyes, lips, genitals, mouth, hands and feet. This swelling also comes with rashes that are raised, itchy and reddish in color. Sometimes, this condition involves larynx too resulting in airway obstruction (life threatening situation). 

 

Types:


Urticaria is broadly classified into two types depending upon the onset and duration of the condition:

 

  • Acute Urticaria: This type is also called “Spontaneous Urticaria”. It is characterized by sudden onset of symptoms. It lasts up to six weeks. It might be caused due to insect bites, infections, medications, some underlying disease or consuming food items like nuts, chocolates, dairy products, fish, eggs, berries, etc. It can also be drug induced. 

  • Chronic Urticaria: This type of urticaria is characterized by gradual onset and longer duration of the disease. It lasts more than six weeks. Most oftenly chronic urticaria is associated with underlying disease or compromised immune system. 

 

Other types of urticaria are grouped as Physical Urticaria. This type occurs due to various physical factors that cause allergic reactions.It can be further classified as follows:


  • PAPULAR URTICARIA: This is a hypersensitivity reaction that occurs in response to insect bites like mosquitoes, beetles, caterpillars, moths, etc. It is very common in children of growing age (between 2 to 10 years of age)

  • COLD URTICARIA: This can occur when the body is exposed to a sudden cold environment. It appears within minutes of exposure to a cold environment. Symptoms vary from person to person, from mild, moderate to seven severe life threatening conditions.

  • CHOLINERGIC URTICARIA: This is an immune reaction that can occur due to sudden rise in body temperature, for example: in case of physical exercise, exposure to heat and sweating.

  • SOLAR URTICARIA: This occurs usually due to exposure to sunlight and the symptoms can come within minutes of exposure.

  • DERMATOGRAPHIC URTICARIA: This is a very common type of physical urticaria. It occurs due to rubbing or scratching the skin. The symptoms of this type of urticaria generally start showing within minutes of rubbing the skin. The symptoms last for about an hour.

 


Diagnosis:

 

  • Clinical diagnosis- The first and foremost diagnostic technique is through the signs and symptoms presented by the individual. The symptoms can include reddish color raised skin rashes that itches and burn sometimes, rashes are of variable shape and size, and are transient in nature (rashes appear and disappear sometimes), and angioedema in severe cases.

  • Skin Prick Test- In this procedure, a small amount of the suspected  substance is injected into the skin with a needle. Now, the reaction is monitored after some time. In case the test is positive, a small red bump over the area is developed, usually within 20 to 30 minutes. This test is commonly used to identify the allergen or triggering factor that causes this disease to the individual. This test is more accurate when the patient is not on antihistamines medication.

  • Lab Test: A blood test is performed to evaluate the amount of IgE antibodies in the blood stream. This is also called Specific IgE ImmunoCAP test. An increase in IgE antibodies is a typical feature of allergic reactions. In this procedure, blood sample is taken from the individual and allergen from the suspected food is added to the blood. The test is positive when there is production of IgE antibodies against the allergen and the individual will be considered allergic to that food item. It is a convenient option for individuals who are not comfortable with the skin prick test.

 

Treatment: 

 

  • Diet control: Once the suspected allergen is confirmed using diagnostic tests, elimination of that allergen containing food can help prevent and treat urticaria effectively.

  • Antihistamines: These are the classic treatment of choice in individuals with allergic reactions. These can be administered orally or applied topically on the skin rash. Antihistamines basically block the action of histamines (protein released in the body in response to allergic reaction). Therefore, the itchiness and inflammation of the skin subsided. These are highly effective and hence, considered first line treatment for allergic reactions.

  • Cold compresses: The individual with urticaria certainly will be irritated due to constant itchiness and discomfort. It can be relieved by using cold compresses on the skin rashes, taking cold showers and avoiding tight clothing.

  • Avoid triggering factors: Avoidance of certain food containing allergens, certain medication and managing stress and anxiety can help reduce the risk of urticaria.

  • Steroids: In advanced cases, where antihistamines are not effective, corticosteroids are prescribed. These are used as topical agents or tablets that reduce inflammation and itchiness. Prednisolone is the most commonly used steroid in this condition. However, long term use of steroids possess certain adverse side effects due to which they are not recommended for a longer period.

  • Immunotherapy: This is used when the outcomes of antihistamines or any other treatment is not satisfactory. Immunotherapy is mostly used in case of chronic urticaria. Cyclosporine and Omalizumab are common immunomodulatory drugs. These drugs modulate the immune system and reduce the symptoms associated with urticaria.

 

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