The trigger for chronic spontaneous urticaria is usually not known.1 What is known is that allergy is not a cause, and like other forms of urticaria, mast cells are activated by your immune system in response to a perceived threat. They then release histamines and other chemicals into the area, which cause the red, itchy hives.2
Although there is no known trigger there are several causes including:3
- Autoreactivity/autoimmunity – this is where your body produces autoantibodies (antibodies that recognise certain substances within your body as foreign) that activate mast cells even though there is no external threat; it occurs in approximately 50% of people with chronic spontaneous urticaria
- Automimmune disorders – there is a strong association between chronic spontaneous urticaria and other autoimmune disorders such as thyroid autoimmune disease
- Autoallergy – this is where a specific allergy antibody recognises something within your body which then activates the mast cell.3
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- Asero R et al. F1000Research 2017; 6:1095.
- Australasian Society of Clinical Immunology and Allergy. ASCIA PCC Hives Urticaria 2021. Available from https://allergy.org.au/patients/skin-allergy/urticaria-hives Accessed August 2021.
- Zuberbier T et al. Allergy. 2018; 73:1393-1414.