What is Urticaria (Hives)?
Urticaria, sometimes called hives, consists of raised, red, itchy welts that appear on the skin as an allergic skin reaction. Urticaria can be classified as follows:
- Acute Urticaria – when it develops suddenly and lasts for less than six weeks. At least 1 in 6 people will experience urticaria at least once in their lifetime. It can affect anyone at any age. Some people experience urticaria multiple times.
- Chronic Urticaria – when it persists for longer than six weeks.
How Does Urticaria Occur?
In most cases, the cause of urticaria cannot be identified. Clusters of welts may appear as an allergic reaction to a trigger such as food, medication, insect stings or bites, infection, or emotional stress. Histamine, a chemical substance in the body, is released in response to the trigger, causing the welts to form.
What Does Urticaria Look Like on the Skin?
The rash usually appears suddenly and can affect any area of the skin in the form of small raised bumps. They resemble mild blisters and are itchy. They are white or red in color and are usually surrounded by a small red ring of skin called a flare. Sometimes neighboring welts merge together to form larger ones. The welts typically last less than 24 hours. Although some disappear, others may reappear, making the rash seem to spread across the entire body.
What Are the Other Symptoms Associated with Urticaria?
In some cases, a condition known as Angioedema develops at the same time as urticaria. In this condition, some fluid also leaks into the deep tissues beneath the skin, causing tissue swelling. The swelling resulting from angioedema can occur anywhere in the body, but the eyelids, lips, and genitals are the most commonly affected areas.
In a small number of cases, a condition known as Urticaria Vasculitis may develop. In this case, the welts persist for more than 24 hours, are often painful, may turn a darker shade of red, and may leave a red mark on the skin when they disappear.
How Is Urticaria Diagnosed?
Your healthcare provider will examine the welts and ask questions about your allergy history regarding things such as:
- Foods
- Medications
- Animal fur
- Exposure to heat, cold, and sunlight
- Viral infections such as colds and flu, which can trigger urticaria in some people
- Skin contact with organic particles, which can cause urticaria in some people — for example, chemicals, rubber, cosmetics, plants, ointments, nettles, etc.
- Physical Urticaria — occurs when urticaria is localized to the skin and appears when the skin is physically stimulated. The most common form is Dermographism, where the patient develops a rash over areas of skin that are subjected to significant pressure or friction.
How Is Urticaria Treated?
One or more of the following measures are recommended to relieve itching and reduce swelling:
- Apply cold compresses
- Avoid heat or rubbing
- Use 1% menthol cream, which can help prevent scratching — however, if left on for too long, it may lead to a return of the urge to scratch
- Take antihistamines to reduce allergic reactions
- If you are able to identify the trigger food, it is advisable to avoid consuming it in the future
- A short course of cortisone tablets is sometimes recommended in acute cases to help reduce skin swelling
- If greater control of the condition is needed, a prescription for Anti-Leukotriene medication may be provided
How Long Will the Effects of Urticaria Last?
The welts can persist from a few hours to several weeks or months. In most cases, the welts eventually disappear without treatment, but medications such as antihistamines help them resolve more quickly. Chronic urticaria, however, lasts much longer. In most cases, it is impossible to identify its cause in up to 50% of patients. Antihistamines are highly beneficial in reducing the complications of this condition.
