Understanding Hives: A Comprehensive Guide to Urticaria

This article was contributed by Dr. Lim Ai Wei, Consultant Dermatologist at Pantai Hospital Klang.

To book an appointment or learn more about Dr. Lim Ai Wei and her clinic, click here.

Hives (Urticaria)

Hives, also known as urticaria, is a common inflammatory skin disorder, characterised by itchy transient bumps on the skin known as wheals. It affects approximately 20 percent of the general population, at some point during their life.

Signs & symptoms

Hives presents as itchy wheals, characterised by well-defined red- or skin-coloured swellings on the surface of the skin. It can occur at any parts of the body, either generalised or localised. The lesions may coalesce as they enlarge, to form larger wheals. Individual lesions are transient, usually appearing and enlarging over the course of minutes to hours and then disappearing within 24 hours, without leaving residual marks on the skin, unless there is trauma from scratching. Hives may be accompanied by angioedema (swelling of the deeper layers of the skin), usually on the face (around the eyes, and lips) hands, feet and genitals. The constant itch and discomfort may disrupt sleep and daily activities.

Classification

• Acute urticaria — hives present for less than six weeks duration
• Chronic urticaria — recurrent hives, occurred most days of the week, for six weeks or longer.

Why do hives occur?

• It is caused by the release of histamine from the activated mast-cells (a type of white blood cells that play a large role in immune system) in the skin that can be spontaneous or triggered by various agents. This leads to itching, dilatation of blood vessels and leakage of fluid into the upper layer of skin (upper dermis). Activation of mast cells deeper in the skin leads to angioedema.
• Immunoglobulin E (IgE) is an antibody that often mediates mast cell activation. There is an an autoimmune component in a subset of patients with chronic urticaria, known as chronic spontaneous urticaria, where presence of autoantibodies in the patient's immune system that target the body's own mast. However, this is not fully understood.

Common causes of Acute Urticaria

• Infections: Viral, bacterial & parasitic
• Medication’s allergy- antibiotics (particularly penicillin and sulphonamides antibiotics), non-steroidal anti-inflammatory drugs (NSAIDs) such aspirin, diclofenac and ibuprofen
• Insects’ sting/bites- bees, wasps, hornets, bedbugs, fleas, and mites
• Food allergy- peanuts, eggs, shellfish, soy, wheat, cow’s milk
• Contact allergy- latex (gloves), plant/pollen

Chronic Urticaria

Chronic urticaria is characterized by the recurrence of itchy wheals and/or angioedema that lasts more than 6 weeks. It can occur in any age group, however it is more common in adults, with a peak age of onset between 20 and 40 years. It affects women more frequently than men. It is classified into chronic spontaneous urticaria and chronic inducible urticaria.

Chronic spontaneous urticaria (CSU)

CSU is an autoimmune condition with no external trigger identified. Although the pathogenesis was not fully understood, evidence suggesting the autoimmune cause which involves both immunoglobin G (IgG)-specific and immunoglobulin E (IgE)-specific autoantibodies, which leads to activation of mast cells, which gives rise to the release of histamine and other inflammatory mediators. CSU is also associated with autoimmune disorders, especially autoimmune thyroid disease and systemic lupus erythematosus (SLE).

Chronic inducible urticaria (CindU)

It is induced by specific physical or environmental stimuli such as heat, cold, sunlight, water, pressure, friction and exercise.  The most one is dermatographism (also known as “skin writing”), in which lesions are created or “written” on the skin by stroking or scratching the skin causing friction. Delayed pressure urticaria is triggered by tight clothing, causing wheals at waistline (i.e., after wearing tight-fitting pants) and bra line.

Diagnosis

1. Clinical assessment: Blood tests- to look for underlying associated autoimmune conditions in chronic Urticaria, include complete blood count (CBC), erythrocyte sedimentation rate (ESR), thyroid-stimulating hormone (TSH), and antinuclear antibody (ANA). 
2. Allergic test: Skin prick tests and IgE tests may help confirm a diagnosis of acute urticaria resulting from allergic reactions to common food allergens, latex allergy, mites, pet dander, pollen
3. Skin biopsy to rule out other conditions with urticarial-like lesions such as urticarial vasculitis (due to inflammation of blood vessels)

Treatment

The mainstay of the treatment is to avoid triggers. Reassurance and patient education play an important role.

The first line therapy consists of non-sedating H1 antihistamines such as cetirizine, loratadine and bilastine, taken on daily basis. This will reduce itchiness, shorten wheal duration, and reduce wheal numbers. If this fails to control the symptoms, the next step involves increasing the dosage of the H1 antihistamine every 2 to 4 weekly until four times the recommended dose.

For chronic spontaneous urticaria that failed to be controlled with antihistamines, Omalizumab should be considered. Omalizumab is a monoclonal anti IgE antibody, that prevent IgE interaction with its receptor on mast cells by binding to the free IgE. Omalizumab is approved for chronic spontaneous urticaria in patients aged 12 and above, at the dosage of 300 mg injections every four weeks for at least six doses.

Ciclosporin is the next line of treatment for chronic spontaneous urticaria with the dose of 2–5 mg/kg/day.

Oral steroids can occasionally be given as rescue treatment for severe flares of acute and chronic urticaria.

When to refer to Skin Specialist?

You should consult a skin specialist for proper evaluation of your condition and provide individualised treatment options for you, if you have:

• Urticaria associated with food or drug allergy
• Recurrent or chronic urticaria (more than 6 weeks) despite high dose of antihistamines
• Signs & symptoms suggestive of urticarial vasculitis
• Diagnostic uncertainity