Viral infections can cause inflammation of the airways of the lungs. When this occurs you may cough, especially when you take a deep breath. After the infection is gone, it is possible for the inflammation to linger. This inflammation can last for several weeks. Sometimes this inflammation may linger for 3 to 6 months. Eventually the inflammation will go away, and then the coughing will stop. This may be what your doctors are calling post viral sensitivity. It is also called reactive airways disease (RAD) and behaves a lot like asthma. On a simple breathing test, called spirometry, this may not show up. This inflammation often clears more quickly when it is treated with an inhaled steroid, which is given to treat asthma. Usually this medicine does not provide immediate relief of symptoms. It may need to be used every day for several weeks to months for it to help.
Asthma is a chronic form of RAD. So when this continues, it is generally considered to be asthma. Some people start to have problems with asthma only after having a lung infection, especially when the infection is severe. Asthma symptoms vary from person to person. The symptoms of asthma are chest tightness, coughing, shortness of breath, and wheezing. Wheezing is the most common symptom. However a cough can be the only symptom of asthma. Each person with asthma could have only one of these symptoms or a combination of any of these symptoms, including all four of them.
With asthma the basic problem is chronic inflammation along with tightening of the smooth muscles that surround the airways of the lungs. An inhaled steroid decreases this inflammation. When used every day, inhaled steroids have the added benefit of preventing inflammation. Bronchospasm is the tightening of the smooth muscles that surround the airways of the lungs. A fast-acting inhaled bronchodilator medicine, like albuterol, reverses the bronchospasm quickly by relaxing the smooth muscles. If you need to use a fast-acting inhaled bronchodilator medicine more than twice in a week this means that the inflammation is not controlled. When a long-lasting inhaled bronchodilator medicine is used every day it prevents bronchospasm. This would have the added benefit of decreasing the need for the fast-acting inhaled bronchodilator medicine.
When this inflammation is not controlled, it increases the sensitivity of the airways to a variety of things that make asthma worse. These asthma triggers vary from person to person. Acid reflux, exercise, infections, and postnasal drip are common triggers. For some people exercise is the only thing that causes asthma symptoms. In people like you who are reasonably fit, symptoms of exercise-induced asthma (EIA) may only occur with the most vigorous activity or exercise.
An exercise challenge is a test used to determine whether or not exercise-induced asthma (EIA) is the problem. The person walks or runs on a treadmill or rides an exercise bicycle. Before and after this exercise spirometry is checked. Spirometry is a simple breathing test that provides detailed information about how the lungs are working. If the spirometry drops by 20% after exercising the test is positive for EIA. If your doctor determines that you have EIA, a fast-acting inhaled bronchodilator medicine, like albuterol, can be used 10 to 15 minutes before exercise. This pre-treating will quickly open the airways and prevent asthma symptoms during exercise. Please read our Exercise-Induced Asthma MedFact at http://www.nationaljewish.org/medfacts/induced.html for more information. You will need to be evaluated further by a pulmonologist. This would be the type of specialist to identify if a lung problem is causing you to continue to cough when you take a deep breath and the best treatment.