Differential Diagnosis for Post-Infection Cough Lasting More Than 3 Weeks
- Single Most Likely Diagnosis
- Postnasal drip syndrome (also known as upper airway secretion syndrome): This is a common cause of chronic cough, especially after a respiratory infection. The justification for this diagnosis is that postnasal drip can persist for weeks after the initial infection has resolved, leading to a prolonged cough.
- Other Likely Diagnoses
- Asthma: Cough can be a prominent symptom of asthma, and respiratory infections can trigger asthma symptoms. The chronic nature of the cough and potential wheezing or shortness of breath support this diagnosis.
- Chronic bronchitis: This condition, often associated with smoking or exposure to irritants, can cause a persistent cough. A history of smoking or exposure to pollutants, along with the chronic nature of the cough, makes this a likely diagnosis.
- Gastroesophageal reflux disease (GERD): GERD can cause a chronic cough due to the reflux of stomach contents into the esophagus, irritating the throat and airways. Symptoms such as heartburn, regurgitation, and the worsening of cough with eating or lying down support this diagnosis.
- Do Not Miss Diagnoses
- Pulmonary tuberculosis: Although less common in many parts of the world, TB is a critical diagnosis not to miss due to its serious consequences if left untreated. A chronic cough, especially with systemic symptoms like fever, night sweats, and weight loss, necessitates consideration of TB.
- Lung cancer: While less likely, lung cancer can present with a chronic cough, especially in smokers or those with a history of exposure to carcinogens. Unexplained weight loss, hemoptysis, or a change in cough characteristics should prompt an investigation for lung cancer.
- Pneumonia (including atypical or fungal pneumonia): In some cases, pneumonia can present with a prolonged cough, especially if the initial infection was not fully treated or if there is an underlying condition affecting the immune system.
- Rare Diagnoses
- Cystic fibrosis: Typically diagnosed in childhood, cystic fibrosis can sometimes present later in life with chronic respiratory symptoms, including a persistent cough.
- Bronchiectasis: A condition characterized by damaged, dilated airways, which can lead to chronic cough, often productive of large amounts of sputum.
- Sarcoidosis: An autoimmune disease that can affect the lungs, causing symptoms such as a chronic cough, shortness of breath, and chest discomfort.
- Eosinophilic pneumonia: A rare condition characterized by an accumulation of eosinophils in the lungs, which can cause a chronic cough among other symptoms.