Abstract
Disorders of mast cell activation can be classified as primary (mastocytosis), secondary (reactive) or idiopathic. This article discusses how to recognise and approach the diagnosis of patients suspected to have symptoms of abnormal mast cell activation. Given the highly varied and often complex symptomatology of such patients, we advocate applying a logical step-wise approach to investigating these patients to ensure the correct diagnosis is made. Treatments of mast cell activation disorders are discussed, dividing them into those that ameliorate the effects of mast cell mediators and those that act to stabilise the mast cell.