Causes of CoughCough is the most common reason why people go to their primary doctor. In some cases, the cough has lasted less than 3 weeks, and is termed an “acute cough”. A cough that has lasted for between 3 and 8 weeks is termed a “sub-acute cough”. And coughing that has been going on for more than 8 weeks is termed a “chronic cough”.
While some people have been coughing for years, the cause of a cough can be determined in at least 90% of these cases. Therapies for cough have a success rate of at least 85%, and therefore treatments should be aimed at the underlying cause, rather than just medications that cover up the cough temporarily.
What Causes a Cough?The cause of a cough is dependent upon how long the symptom has been present. For example, the causes of an acute cough may be quite different from the causes of a chronic cough. In at least 25% of cases of a chronic cough, there are at least 2 medical conditions causing the cough in the person.
What Causes an Acute Cough?The most common causes of an acute cough include:
- The common cold
- Acute sinusitis
- Pertussis (whooping cough)
- Chronic obstructive pulmonary disease (COPD) exacerbations
- Allergic rhinitis
- Non-allergic rhinitis
The cause of the acute cough is usually determined by the person’s history and physical exam. Some experts will use an antihistamine/decongestant combination (such as Dimetapp or the equivalent generic) in the treatment of an acute cough due to the common cold. Newer antihistamines/decongestants, such as Claritin-D (loratadine/pseudoephrine), do not seem to be as helpful.
People who continue to cough despite the treatment for a common cold, or who have other signs of an acute sinusitis, are given a course of antibiotics aimed at sinusitis as a reason for the acute cough. Children appear particularly prone to having a cough as the only sign of a sinus infection.
Those with underlying COPD (emphysema or chronic bronchitis) may have exacerbations with an increase in cough, shortness of breath, wheezing and change in mucus production and color. Antibiotics are typically given to these people with an acute cough.
Whooping cough, or Pertussis, is becoming more in certain communities, and vaccination does not always provide complete protection. People with Pertussis will have severe episodes of coughing, often with vomiting after the cough. Treatment with antibiotics helps if given early in the infection; otherwise the cough may become chronic and last for many weeks.
Rhinitis (allergic and non-allergic) may also cause a cough that is related to post-nasal drip (phlegm draining from the back of the nose into the throat). However, this may be a very different cough from the above, and more of a throat clearing type of cough. Allergic rhinitis will respond to various allergy treatments, while non-allergic rhinitis may only respond to decongestants or various prescription nasal sprays.
What are the Causes of Sub-acute Cough?For a cough that has lasted for between 3 and 8 weeks, the most common causes are:
A post-infectious cough is a cough that has persisted after a common cold or other viral respiratory tract infection, in which there is no pneumonia. It can be a result of post-nasal drip or bronchitis. These symptoms may resolve without treatment, or may become an acute sinusitis requiring antibiotics. Some experts will give a trial of a decongestant/antihistamine combination (such as Dimetapp or the generic equivalent) for one week, and if this fails, a trial of antibiotics.
If a person also complains of shortness of breath, wheezing, or chest tightness, then asthma may be the cause of the cough. Usual treatments for asthma would then be given.