MCAS can occur at any age and affects multiple organs, resulting in a wide range of symptoms including:6
- Skin – facial flushing, itching and hives.1,9
- Gastrointestinal – abdominal pain, cramping, diarrhoea, nausea and vomiting.1,9
- Respiratory – wheezing, chest tightness.1
- Nasocular – pruritus, nasal stuffiness, conjunctival injection.1
- Cardiovascular – hypotension, tachycardia, chest pain/tightness.1,9
- Brain – headache, lightheadedness, brain fog*.5,9
- Systemic – fatigue, anaphylaxis.1,5
* Acute episodes of mast cell mediator release and activation may cause transient cognitive impairment when accompanied by hypotension or other significant mediator effects. However, chronic or persistent brain fog is not established to be a direct consequence of excessive mast cell activation, and alternative causes should be investigated.
Disclaimer
Last updated: 12 December 2025
Please note that this information is provided for general educational purposes only and does not replace medical advice, nor should it be used in place of consultation with a qualified health professional. While care has been taken to reflect current information based on reputable scientific source material at the time of writing, and TAMS will continue to update information periodically, omissions or inconsistencies may occur as scientific knowledge evolves.
