The wheal and angioedema associated with chronic urticaria (CU) is caused by the release of chemicals that are involved in your immune system – such as histamines – that activate sensory nerves, dilate blood vessels and then allow fluid to leak into surrounding tissues.¹

As mentioned in the Types of Urticaria section, inducible urticaria is caused by physical or environmental factors known as “triggers”. Another type of urticaria called spontaneous (idiopathic) urticaria does not have a known trigger.

Common triggers for urticaria include^1,2:

• Certain food types, for example, eggs, dairy and shellfish
• Pollen and other airborne allergens
• Insect bites
• Latex 

Other triggers for chronic inducible urticaria can include:¹

In addition to NSAIDs, drugs like beta-lactams are known triggers, with NSAIDs aggravating skin lesions in up to 50% of patients.³ 

References

1. Chronic inducible urticaria. DermNet®. 2023. Available from: https://dermnetnz.org/topics/chronic-inducible-urticaria. Last accessed April 2025.
2. Hives and angioedema – Symptoms and causes - Mayo Clinic. Available from: https://www.mayoclinic.org/diseases-conditions/hives-and-angioedema/symptoms-causes/. Last accessed May 2025.
3. Hon KL, Leung AKC, Ng WGG, Loo SK. Chronic Urticaria: An Overview of Treatment and Recent Patents. Recent Patents on Inflammation & Allergy Drug Discovery. 2019 Aug 5;13(1):27–37.