Viral illnesses, asthma, allergies, bronchospasm and exposure to respiratory irritants are among the main causes of dry cough, according to WebMD. Dry cough is defined as a cough that does not bring up any mucus. Someone with a viral illness may have a dry cough for several weeks after other symptoms dissipate. The cough typically worsens at night.
Mild asthma causes dry cough along with shortness of breath, wheezing and tightness in the chest, according to WebMD. People with hay fever and other allergies sometimes develop a persistent dry cough. Healthline says the cough develops in response to the irritants found in the throat.
The University of Minnesota Medical Center defines bronchospasm as a spasm of the muscles around the airways. This condition may cause coughing or wheezing when a person exhales. Many people with bronchospasm have asthma, but asthma is not the only cause.
Cough is one of the symptoms of a condition called chemical pneumonitis. MedlinePlus says this condition occurs in people who are exposed to chemicals or chemical fumes. Smoke, fertilizer dust, chlorine gas and pesticide fumes are among the most common causes. In cases of acute pneumonitis, the cough may be accompanied by abnormal lung sounds, burning in the chest and difficulty breathing. Chronic pneumonitis may cause rapid breathing and shortness of breath with mild exertion.