Urticaria and angioedema

Urticaria and Angioedema are two related but distinct conditions that affect the skin and mucous membranes, respectively. Both conditions are characterized by swelling, redness, and itchiness, but they differ in their specific manifestations and underlying causes.

Urticaria (Hives)

Urticaria, commonly known as hives, is a skin reaction that results in red, raised, itchy welts. These welts can vary in size and appear anywhere on the body. Urticaria is often caused by an allergic reaction to food, medication, or other allergens. However, it can also result from non-allergic causes such as stress, infection, or autoimmune disorders.

Causes

The primary cause of urticaria is the release of histamine and other inflammatory mediators from mast cells in the skin. This release can be triggered by:

• Allergic reactions to food, medication, insect stings, or latex
• Physical stimuli such as pressure, cold, heat, exercise, or sun exposure
• Infections, including viral, bacterial, and parasitic infections
• Autoimmune disorders
• Stress

Symptoms

Symptoms of urticaria include:

• Red or skin-colored welts that can appear anywhere on the body
• Welts that vary in size, shape, and are often itchy
• Swelling and redness around the welts
• Flare-ups that occur suddenly and may resolve quickly or persist for several days

Angioedema

Angioedema is similar to urticaria but affects deeper layers of the skin and mucous membranes. It is characterized by sudden, severe swelling of the skin, mucous membranes, or both. Angioedema can occur on its own or in conjunction with urticaria.

Causes

Angioedema can be caused by:

• Allergic reactions, similar to those causing urticaria
• Hereditary factors, as seen in hereditary angioedema (HAE), which is a rare genetic condition
• Medications, particularly ACE inhibitors used to treat high blood pressure
• Idiopathic causes, where no specific trigger is identified

Symptoms

Symptoms of angioedema include:

• Swelling of the deeper layers of the skin, often around the eyes, lips, and sometimes the genitals, hands, and feet
• Swelling of the mucous membranes, potentially affecting breathing or swallowing
• Pain or warmth in the affected areas
• In severe cases, difficulty breathing if the swelling affects the throat

Diagnosis

Diagnosis of urticaria and angioedema involves a thorough medical history and physical examination. Additional tests may include:

• Allergy testing to identify potential allergens
• Blood tests to check for underlying health conditions
• In cases of hereditary angioedema, genetic testing

Treatment

Treatment for urticaria and angioedema focuses on relieving symptoms and preventing future episodes. Common treatments include:

• Antihistamines to reduce itching and swelling
• Corticosteroids for severe cases
• Epinephrine for life-threatening reactions, particularly in cases of angioedema affecting the throat
• Avoidance of known triggers
• For hereditary angioedema, specific treatments such as C1 inhibitor concentrates, bradykinin receptor antagonists, and kallikrein inhibitors

Prevention

Preventing episodes of urticaria and angioedema involves identifying and avoiding triggers. For individuals with hereditary angioedema, preventive medications may be recommended.