Definition

What is Urticaria?

Urticaria (also known as hives) is a disease characterized by the sudden development of itchy pale red bumps (wheals, hives) on the skin. Wheals may present in variable sizes and shapes and have a fleeting nature, with the skin returning to its normal appearance in around 24 hours. These wheals may appear in certain parts of the body, or they may be generalized.
Hives are often accompanied by swelling known as angioedema. A few patients have only angioedema without hives.

Angioedema is a swelling in the deeper skin layers. The borders of the swellings are therefore less visible, and their color is often not evidently different from the normal skin. Angioedema frequently occurs on the face, lips, hands, and feet. Itching is not frequent, and patients may complain of pain. Its duration is around 48 to 72 hours.
The name “urticaria” originates from the Latin name “Urtica dioica” due to its similarity to the effect produced by this European nettle coming in contact with the skin.

Urticaria is a common disease that affects around 1 in 5 people at some point in their lives. Urticaria may be acute or chronic. In acute urticaria, skin lesions resolve completely within a few days, while in chronic urticaria, lesions persist for more than six weeks. Chronic urticaria is further classified as chronic spontaneous urticaria (CSU) when triggers are not identified and chronic inducible urticaria (CIndU) when it is triggered by physical factors such as heat, cold, pressure, or vibration.
Acute urticaria (AU) is more common in children, while chronic urticaria (CU) mainly affects women between 25 and 35 years.

Urticaria can affect the patient’s quality of life. It is disfiguring, unpredictable and intensely itchy, which can interfere with sleep and activity. Urticaria can become unbearable, causing emotional distress and possibly leading to depression.

Acute urticaria (AU) is more common in children, while chronic urticaria (CU) mainly affects women between 25 and 35 years.

History of Urticaria

Hippocrates (460-377 BC) described elevated itchy lesions caused by nettles and mosquitoes, which he called “knidosis”, after the Greek word for nettle (knido). In the 10th century, Ali Ibu Al-Abbas called it “essera”, which in the Persian language means elevation. The word “urticaria” was first introduced in 1769 by William Cullen in his book “Synopsia Nosalogiae Methodica”. Jean Astruc (1684-1766), the founder of modern dermatology and histology, showed that the weal (or wheal) was due to local obstruction of oedema. Dale and Laidlow showed that the tissue contained an amine that affected smooth muscles and vessels and called it histamine. In the last few decades, great advances in the diagnosis and treatment of urticaria have occurred.

The Course of Urticaria

HOW DOES URTICARIA DEVELOP?

Urticaria develops when specific immune cells in the body, called mast cells, become activated. This results in the release of chemicals such as histamine, causing itching, redness, and swelling. Hives appear suddenly and disappear within several hours, usually within less than 24 hours and may appear once again in other areas of the body.
Urticaria develops either after an allergic trigger (usually recognized by the patient) such as food, medication, insect stings and/or physical contact with allergens or after exposure to physical factors such as heat, cold, vibration, and pressure. This is why it is called inducible urticaria or spontaneously with no identified trigger. Non-allergic triggers may occur after viral illnesses. However, most chronic spontaneous urticaria appears suddenly without any identified trigger.

WHAT IS THE PROGNOSIS?

In acute urticaria, it is crucial first to identify the allergic triggers such as food or drugs to avoid further exposure, as acute hives may be part of a severe allergic reaction (called anaphylaxis) that may be life-threatening if untreated. Furthermore, avoidance of the trigger is the most crucial step to avoid recurrence in the future.
In chronic spontaneous urticaria (CSU), the trigger is unknown and usually non-allergic. It can be frustrating, as it affects how an individual looks and is unpredictable. In many cases, affected people avoid many foods unnecessarily, without benefit. The good news is that CSU is a benign condition as it is not life-threatening, not contagious, and is easily treatable in most people. They are rarely permanent; almost 50% of affected people are hive-free within 1 year.
Inducible urticaria tends to be long lasting for years but eventually disappears.

CAN URTICARIA BECOME DANGEROUS?

Most cases of acute and chronic urticaria are non-allergic and, although bothersome, are not dangerous. The exception is acute urticaria due to allergy, as it may progress to anaphylaxis and may be life-threatening if left untreated.