9th June 2025

Classification

Acute Urticaria

Acute urticaria is the most common form of the condition. The lifetime prevalence of acute urticaria is approximately 20%. Possible triggers include: 

• Infections (viral and bacterial), 
• Allergens e.g food allergens 
• Drugs – typically ACE inhibitors (due to neurokinin accumulation) and NSAIDs
• Emotional stress 

 Typically, it resolves in hours to days. It is more common in atopic individuals. Severe, acute allergic urticaria may lead to anaphylactic shock. Acute urticaria does not usually involve the lung tissue or cause wheeze in the milder forms, but in anaphylaxis or severe urticaria, this is part of the clinical picture. 

Acute urticaria coupled with fever can be the first sign of COVID-19 infection although this is an uncommon presentation.

Chronic Urticaria

Chronic urticaria is a more severe form of the condition, and it is characterized by the persistence of symptoms for more than six weeks. The symptoms of chronic urticaria are similar to those of acute urticaria, but they can last for several months or even years. Wheeze and respiratory symptoms are not a feature of chronic urticaria. 20-45% of patients presenting with acute urticaria will subsequently develop chronic urticaria.