What causes cough?Coughing is usually a reflex response of the body caused by an irritation in the throat or windpipe. A reflex response means that the body does something automatically, without a person thinking about it. This reflex helps to protect the lungs from bacteria, viruses, dust, and other damaging substances. However, people can cough on purpose if they want or need to.
There are many possible causes of a cough, ranging from allergies to lung infections and cancer.
Acute cough is most often caused by the common viral upper respiratory tract infection. Cold viruses often causes a postnasal drip and that causes a cough. This is the most common cause for a cough. The cough is usually secondary to stimulation of nasal, pharyngeal, and laryngeal mucosa receptors. This results from the secretions of the nose and sinuses draining into the throat. A dry cough may follow viral illnesses and may last up to several weeks. Chronic cough may be caused by a variety of underlying diseases including asthma, cystic fibrosis, allergies, GERD and chronic post nasal drip. Smoking is a major cause of chronic cough. Croup is characterized by a barking, "seal-like" cough caused by a virus. Pertussis or whooping cough is an infection that is characterized by a severe cough where the child has difficulty catching his breath with the coughing episodes and may turn blue with coughing.
Pneumonia, which is an infection in the lungs. It may be caused by viruses or bacteria. There is also an unusual organism called mycoplasma, which causes the classic "walking pneumonia". Children with pneumonia can barely appear sick with low-grade fever and a mild cough or be very ill with high fevers and labored breathing.
Asthma may cause coughing and wheezing. This may be triggered by viruses, exercise or an allergic trigger like dust, smoke, mold or pets. Asthma most commonly presents with shortness of breath and wheezing but there are some patients with asthma whose main symptom will be cough. These patients with so called "cough-variant asthma" sometimes notice that their cough is worse after exercise, exposure to cold air, or exposure to different allergens.
Foreign body aspiration should be suspected if there is a history of a coughing or choking episode with eating, especially with small hard foods like nuts or popcorn. Sinusitis may cause a cough especially at night or in the mornings.
"Spitting up" or gastroesophageal reflux in babies under a year may trigger coughing because of small amounts of aspiration of food into the lungs. Wheezing or recurrent pneumonia may be associated with reflux. Gastroesophageal reflux is a very common cause of cough and clues to its presence may include cough after eating, cough when laying flat (for example, when going to bed), and cough when waking up in the morning.
Certain medications (ACE inhibitors for hypertension) cause coughing as a side effect. Medications which can commonly cause cough include angiotensin converting enzyme inhibitors (ACE inhibitors) which are used to treat high blood pressure or heart failure. Some of the common ACE inhibitors include Zestril, Capoten, and Vasotec. Often the cough associated with these drugs develops many months after starting their use.