Cough-variant asthma is a type of asthma where the main symptom is a dry, non-productive cough that lasts longer than six to eight weeks. Anyone can get cough-variant asthma, but it is most common in younger children with asthma. Often times, people with cough-variant asthma don’t display other classic asthma symptoms, such as wheezing and chest tightness; however, cough-variant asthma can eventually lead to classic asthma symptoms.
People with cough-variant asthma may experience an increase in coughing from typical asthma triggers, such as exercise, dust and allergens, or cold air. Coughing may also occur after an upper respiratory infection. Some medications have been known to cause cough-variant asthma, including beta blockers and aspirin.
Cough-variant asthma can be hard to diagnose. The cough is generally the only symptom and can often be misdiagnosed as bronchitis or other common cause of coughing. People with cough-variant asthma can have normal chest x-rays and spirometry tests, which are generally used to diagnose those with classic asthma. There are two ways to successfully diagnose cough-variant asthma:
- Methacholine challenge test – Inhaling increasing amounts of methacholine, which will make airways spasm and narrow in everyone, even non-asthmatics. Lung function is measured using spirometry before and after administrating the methacholine. If lung function drops by at least 20%, the test is positive for asthma.
- Treating the cough with asthma medication – If the cough responds to the asthma medication, it’s cough-variant asthma.
Cough-variant asthma is treated through the use of control and quick-relief medication, the same way as classic asthma is.