Urticaria, or hives, is a condition that affects up to 20% of the population at least once in their lifetime. While the source of the condition is immunology-related, it is often categorised as a dermatological condition due to its manifestation as small, pink/red, itchy bumps (welts) on the skin. They may occur on any part of the body and, if many in number, may fuse together to form larger rash-like patches in a given area.

Urticaria is classified as:

• acute – usually a single attack linked to a particular event, clearing off completely within days or a few weeks
• chronic – recurrent attacks where rashes may be persistent or appear every now and then over months or years

Symptoms

Urticaria is characterised by the appearance of itchy red (or sometimes skin-coloured) bumps on the skin that usually turn white at the centre when pressed (known as ‘blanching’), and that may feel slightly warmer than the surrounding skin. The bumps, or welts, may vary in size, shape and intensity from one attack to another, and from one person to another.

Complications

While urticaria by itself does not pose a threat to the patient, about a quarter of acute urticaria patients and around a half of chronic urticaria patients sometimes go on to develop angioedema. This is caused by a build-up of fluids and can result in severe swelling in deeper layers of mostly the lips, eyes, hands, feet and genitals.

In addition, the recurrence of chronic urticaria may have an emotional impact on some sufferers, affecting their mental health in the form of anxiety, stress or depression.

Causes

Urticaria is initiated by some sort of trigger factor that causes the release of high levels of histamines and other chemical that result in an allergic reaction. This involves the dilation of blood vessels under the skin which then leak fluid into the tissue below the skin, resulting in the formation of itchy bumps.

The cause of acute urticaria may remain unknown in nearly half the cases. Known triggers include:

• foods such as shellfish, peanuts and other nuts, eggs, some cheeses
• physical factors such as pressure, temperature changes, sunlight, cold, water, exercise
• environmental factors such as pollen, dust mites, chemicals
• certain materials such as latex (e.g. gloves)
• insect stings and bites
• scratching the skin
• certain medications such as antibiotics, NSAIDs
• infections ranging from the simple cold to more complex infections such as HIV
• anxiety and stress

Chronic urticaria may be associated with trigger factors such as:

• autoimmune diseases such as lupus, rheumatoid arthritis
• chronic illnesses and infections such as intestinal parasites, hypo/hyper-thyroidism, hepatitis
• food additives such as salicylates
• alcohol and caffeine consumption
• physical factors such as prolonged pressure (e.g. wearing tight clothes), heat, cold, water
• insect stings and bites
• certain medications such as NSAIDs, codeine
• anxiety and stress

Diagnosis

Observation of the above-mentioned symptoms and a simple examination by a GP usually suffices in the process of diagnosing urticaria. The GP may subsequently ask further questions from the patient in order to try to determine the cause of the symptoms. In addition, the doctor may also refer the patient for a full blood count (FBC) and/or an allergy test in order to determine if there may be any other underlying conditions causing the observations.

It is important to differentiate between urticaria and anaphylaxis, the latter of which should be treated as a medical emergency. Urticaria symptoms may sometimes indicate the onset of anaphylaxis, which then continues on to much more severe symptoms such as swelling of lips, eyes, hands and feet, narrowing of airways leading to breathing difficulty, abdominal pain, nausea, vomiting, feeling light-headed and collapsing. In such situations, medical attention should be sought immediately.

Prevention

There is no means of preventing the incidence of urticaria unless the cause of the symptoms is known – in which case the trigger factor(s) could be avoided.

Treatment

Often, extensive treatment is not required for urticaria. A simple dose (short-term or long-term) of antihistamines usually helps to alleviate symptoms, and can generally be obtained over the counter at a pharmacy. Commonly prescribed antihistamines include cetirizine, loratadine, fexofenadine (all non-drowsy) and chlorphenamine, promethazine and hydroxyzine (these can cause drowsiness). Strength, dosage and duration of the course would have to be determined or altered as per each individual’s condition and response to treatment.

In more severe cases where antihistamines prove to be ineffective, a doctor may prescribe a short-term dose of oral corticosteroids. It should be borne in mind that long-term or frequent use of steroids is not recommended as it could cause health-related complications in the long run.

Cover illustration adapted from Depositphotos