Brittle asthma is an older term used to describe a severe type of asthma. People with brittle asthma have big variations in their symptoms and breathing tests despite being on high doses of asthma treatment. It's also used to describe people who get sudden, severe asthma attacks occurring 'out of the blue', despite having well-controlled asthma.
This is a companion discussion topic for the original article at https://patient.info/chest-lungs/brittle-asthma