Synopsis
Distinguish modifiable difficult asthma from genuinely severe disease, recognise eosinophilic and broader type 2 traits, and refer safely for specialist phenotype-led treatment.
- Difficult asthma remains uncontrolled for any reason; severe asthma is the smaller subset that stays uncontrolled despite confirmed diagnosis, optimised adherence, technique, exposures, comorbidity and high-intensity treatment.
- Before adding specialist drugs, revisit whether symptoms are asthma: inducible laryngeal obstruction, dysfunctional breathing, obesity, cardiac disease, bronchiectasis and anxiety can coexist or mimic poor control.
- Count attacks, urgent care, systemic corticosteroid courses and functional restriction; a symptom score alone can miss serious future risk.
Key red flags
Repeated systemic corticosteroid courses, emergency attendance, admission, previous ventilation, rising reliever use or abrupt loss of control predicts future harm even when the person appears comfortable at a planned review.
Investigation priorities
Confirm variable airway disease before labelling severe asthma.
Management branches
Symptoms or attacks persist despite apparently high-intensity asthma treatment.
- Reconstruct the diagnosis from symptom pattern, objective variable airflow evidence, previous attacks and response, considering airway and non-airway mimics.
- Observe every inhaler, reconcile prescriptions with collections and daily use, and switch device or education strategy when delivery is unreliable.
Key medicines
High-intensity inhaled corticosteroid-formoterol maintenance and reliever therapyUse the current NICE step and exact locally selected inhaler strength, maintenance schedule and as-needed limit after specialist technique and adherence review.
Mepolizumab for eligible severe eosinophilic asthmaFor adults and adolescents, 100 mg subcutaneously once every four weeks as specialist-initiated long-term add-on treatment under current NICE criteria.