Overview of Urticaria and protocols required to be followed for the management of urticaria

What is Urticaria?  

Urticaria, commonly known as welts or hives, refers to raised, erythematous wheals caused by the release of histamine and other vasoactive substances from mast cells. When swelling is superficial, urticaria eventuates. When the swelling is deeper, angioedema occurs typically affecting the lips and peri-orbital areas of the face, and may also involve the upper airways.    

Classification of Urticaria 

Urticaria is classified as Acute and Chronic  

Chronic spontaneous urticaria is a condition which persists for more than 6 weeks in duration and occurs in the absence of an identifiable provoking factor.

Chronic urticaria may be autoimmune, induced by physical stimuli, or idiopathic. NSAIDs, foods, alcohol, stress, and infections may aggravate chronic urticaria but are rarely the cause.

Chronic spontaneous urticaria may be associated with other autoimmune conditions including autoimmune thyroid disease, vitiligo, insulin-dependent diabetes, rheumatoid arthritis, and pernicious anemia.     

Acute Urticaria describes episodes of urticaria occurring over a period of less than six weeks.  Acute urticaria is more commonly seen in children. Approximately 50% of cases of Acute urticaria are idiopathic.

Physical Urticaria occurs in localised area after getting in contact with physical stimulus. It persists as chronic recurring condition. Dermatographism is the most common form of physical urticaria, triggered by smoking or scratching of the skin or contact with clothes or other objects 

Types of Physical Urticaria  

• Contact Urticaria
• Cholinergic Urticaria
• Delayed Pressure Urticaria
• Cold Urticaria
• Solar Uricaria
• Vibratory Urticaria

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Test to identify causes of urticaria  

Various test to identify causes of urticaria are Complete blood count, Erythrocyte sedimentation rate and C reactive protein are important investigations for diagnosis of infections in urticaria. Autologous serum skin test is a simple office procedure for diagnosis of auto reactive urticaria. Closed ball point pen tip is a simple test to diagnose dermographism.

What causes Urticaria? 

Urticaria occurs due to the release of chemical mediators including histamine from mast cells in the skin. These mediators activate sensory nerves and cause small blood vessels to leak. This process is usually triggered by various immune pathways such as circulating IgE antibodies.    

Allergens in food or medicine may sometimes cause acute urticaria. For young babies, in whom urticaria is rare cow’s milk allergy is the common cause.

As children grow up, they may react to different foods, including nuts, fruits or shellfish if they become allergic. Bee and wasp stings can cause acute urticaria. 

Chronic spontaneous urticaria may be autoimmune, the patient’s own antibodies that release histamine from mast cells.

Some people with urticaria may have other conditions, such as thyroid disease or other autoimmune disorders. 

What are the treatment options for urticaria?   

• Antihistamine tablets block the effect of histamine by reducing itch and the rash in most people but may not relieve urticaria completely. If urticaria occurs frequently, antihistamines should be taken regularly every day. There are many different types, including non-sedating and sedating antihistamines, as well as short acting and long acting types. They are known as H1 antihistamines.
• A different type of antihistamine called H2 antihistamines that are usually used to treat stomach acid symptoms can be added if standard H1 antihistamines are insufficient on their own.
• If antihistamine tablets are not helpful, your doctor may recommend other medicines, including montelukast that is usually used as an add-on treatment of asthma.
• Oral steroids can occasionally be given as rescue treatment for severe flares of acute and chronic urticaria but are generally not necessary as their potential side effects usually outweigh the benefits in this condition.
• Treatments that act by suppressing the immune system may be beneficial for the most severely affected people not responding to the treatments outlined previously, especially those with autoimmune urticaria.

Very rarely injections of adrenaline (epinephrine) may be required if there are breathing problems caused by angio-oedema.

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