Urticaria is migratory, erythematous, pruritic plaques. Urticaria is classified as acute (< 6 wk) or chronic (> 6 wk). The term angioedema refers to deep dermal or subcutaneous swellings. Isolated angioedema without wheals may be due to deficiency of C1 esterase inhibitor.

Causes

There are multiple causes of urticaria, most of which involve histamine release

In acute urticaria, this generally represents a hypersensitivity reaction. Some allergens directly trigger histamine release independently of

IgE-mediated allergy

 

• Parasitic infestations
• Viral infections
• Drugs like aspirin, NSAIDS, captopril, opiods and others
• Physical stimuli like cold, sunlight, exercise, rubbing

 

Most cases of chronic urticaria are idiopathic, although some represent recurrent undiagnosed hypersensitivity reactions

 

Symptoms

Hives appear as small round wheals, rings or large patches and may change shape

They usually itch and may be surrounded by a red flare

About 40 percent of people with chronic hives also have angioedema - swelling of the skin that may occur around the eyes and lips, hands, feet, genitalia and inside the throat

Swelling in the throat can obstruct breathing and requires emergency treatment

Risk factors

• Women — chronic hives occur twice as often in women as they do in men?
• Older adult
• History of hives or angioedema before
• History allergic reactions
• Disorder associated with hives and angioedema, such as lupus, lymphoma or thyroid disease
• Family history of hives, angioedema or hereditary angioedema

Diagnosis

Complete blood test- mainly esionphil count

Allergy test- IgE levels estimation, skin patch and prick test

Complications

Angioedema- when swelling occurs inside your mouth or throat — complications can include difficulty breathing

Anaphylactic shock (anaphylaxis) is a serious allergic reaction involving your heart or lungs.

Prevention

• Avoid known triggers. These may include certain foods or medications or situations such as temperature extremes or emotional stress
  
• Avoid medications that may trigger hives. These include aspirin, codeine and any medications your doctor told you not to take
• Avoid alcohol. It causes blood vessels to expand and can worsen symptoms. In some people alcohol triggers urticaria

Treatment

• Oral antihistamines- Cetrizine, loratidine, fexofenadine, hydroxyzine, diphenhydramine etc
• Oral corticosteroids such as prednisone- but are only used short term for severe hives or angioedema because they can cause serious side effects
• For a severe attack of hives or angioedema, you may need an emergency injection of adrenaline (epinephrine) and a trip to the emerge.