A cough is not a disease, but can be a common symptom of different upper and lower respiratory tract diseases. Even if you do not have a lung disease, you may cough.
A cough can happen when something irritates your nerve endings, called cough receptors. These nerve endings are in many areas inside your body, from your head and neck area, to just above your navel (belly button). Inhaling particles, vapors, smoke, fumes, dust, or cold air may irritate these receptors and may make you cough.
In healthy adults, most acute cough syndromes are due to viral respiratory tract infections. Additional features of infection such as fever, nasal congestion, and sore throat help confirm this diagnosis. Dyspnea (at rest or with exertion) may reflect a more serious condition, and further evaluation should include assessment of oxygenation (pulse oximetry or arterial blood gas measurement), airflow (peak flow or spirometry), and pulmonary parenchymal disease (chest radiography).
The timing and character of the cough are not very useful in establishing the cause of acute cough syndromes, although cough-variant asthma should be considered in adults with prominent nocturnal cough, and persistent cough with phlegm increases the likelihood of chronic obstructive pulmonary disease (COPD).
The presence of posttussive emesis or inspiratory whoop in adults modestly increases the likelihood of pertussis, and the absence of paroxysmal cough and the presence of fever decreases its likelihood. Uncommon causes of acute cough should be suspected in those with heart disease (heart failure) or hay fever (allergic rhinitis) and those with occupational risk factors (such as farmworkers).
Persistent and chronic cough
Cough due to acute respiratory tract infection resolves within 3 weeks in the vast majority (more than 90%) of patients. Pertussis should be considered in adolescents and adults with persistent or severe cough lasting more than 3 weeks, and in selected geographic areas where its prevalence approaches 20% (although it’s exact prevalence is difficult to ascertain due to the limited sensitivity of diagnostic tests).
When angiotensin-converting enzyme (ACE) inhibitor therapy, acute respiratory tract infection, and chest radio-graph abnormalities are absent, most cases of persistent and chronic cough are due to (or exacerbated by) postnasal drip (upper airway cough syndrome), asthma, or gastroesophageal reflux disease (GERD), or some combination of these three entities. Approximately 10% of cases are caused by non-asthmatic eosinophilic bronchitis.
A history of nasal or sinus congestion, wheezing, or heartburn should direct sub-sequent evaluation and treatment, though these conditions frequently cause persistent cough in the absence of typical symptoms. Dyspnea at rest or with exertion is not commonly reported among patients with persistent cough; dyspnea requires assessment for chronic lung disease, HF, anemia, pulmonary embolism, or pulmonary hypertension.
Can a cough spread infection?
Cough can be a way of spreading infection to others. Influenza (the flu) and tuberculosis (TB) are examples of infections that can be spread by coughing infected droplets into the air. While a cold virus (the common cold) can be passed on to others by coughing, cold viruses are much more likely to be spread to others by hand to nose contact. Hand-to-nose contact is when you shake hands with someone who has the infection or touch something that has the cold virus on it and then your touch your nose or eyes.
To help decrease the spread of infection, you should:
- Cover your mouth and nose with a tissue when coughing or sneezing. You don’t want to spread germs to others.
- When a tissue is not available, cough or sneeze into your upper sleeve or elbow, not your hands.
- Dispose of used tissues into a waste basket.
- Avoid spitting as it can cause a mist that may infect others.
- Ask for and wear a facemask when entering a healthcare facility if you are coughing or have cold symptoms.
- Wash your hands often and for at least 20 seconds using soap and water.
- Use an alcohol-based hand rub (sanitizer) when soap and water are not available.
When should I contact my healthcare provider about my cough?
- Any time that your cough concerns you, you should discuss with your healthcare provider. It is very important that you contact your healthcare provider if:
- You spit up blood when you cough.
- You have chest pain or trouble breathing when you cough.
- Your coughing makes you vomit.
- You have an unexplained weight loss.
- Your cough began after you were in close contact with someone who has whooping cough.
- Your cough lasts more than 8 weeks.
- Your cough starts to get better and then gets worse.
- If you have a lung problem such as asthma or cystic fibrosis (CF) and have frequent or chronic cough, you should talk to your healthcare provider if the pattern of the cough changes
Treatment of acute cough should target the underlying etiology of the illness, the cough reflex itself, and any additional factors that exacerbate the cough. Cough duration is typically 1–3 weeks, yet patients frequently expect cough to last fewer than 10 days. Limited studies on the use of dextromethorphan suggest a minor or modest benefit; dextromethorphan should be avoided in children and adolescents because of concerns about misuse.
When influenza is diagnosed (including H1N1 influenza), oral oseltamivir or zanamivir or intravenous peramivir are equally effective (1 less day of illness) when initiated within 30–48 hours of illness onset; treatment is recommended regardless of illness duration when patients have severe influenza requiring hospitalization.
In Chlamydophila or Mycoplasma-documented infection or outbreaks, first-line antibiotics include erythromycin or doxycycline. However, antibiotics do not improve cough severity or duration in patients with uncomplicated acute bronchitis. In patients with bronchitis and wheezing, inhaled beta-2-agonist therapy reduces severity and duration of cough. In patients with acute cough, treating the accompanying postnasal drip (with antihistamines, decongestants, or nasal corticosteroids) can be helpful.
When pertussis infection is suspected early in its course, treatment with a macrolide antibiotic is appropriate to reduce organism shedding and transmission. When pertussis has lasted more than 7–10 days, antibiotic treatment does not affect the duration of cough, which can last up to 6 months. Early identification, revaccination with Tdap, and treatment of adult patients who work or live with persons at high risk for complications from pertussis (pregnant women, infants [particularly younger than 1 year], and immunosuppressed individuals) are encouraged.
When empiric treatment trials fail, consider other causes of chronic cough such as obstructive sleep apnea, tonsillar or uvular enlargement, and environmental fungi. The small percentage of patients with idiopathic chronic cough should be managed in consultation with an otolaryngologist or a pulmonologist; consider a high-resolution CT scan of the lungs. Treatment options include nebulized lidocaine therapy and morphine sulfate, 5–10 mg orally twice daily.
Sensory dysfunction of the laryngeal branches of the vagus nerve may contribute to persistent cough syndromes and may help explain the effectiveness of gabapentin in patients with chronic cough. Speech pathology therapy combined with pregabalin has some benefit in chronic refractory cough. In patients with reflex cough syndrome, therapy aimed at shifting the patient’s attentional focus from internal stimuli to external focal points can be helpful. Proton pump inhibitors are not effective on their own; most benefit appears to come from lifestyle modifications and weight reduction.