When clinical tests do not give any indication of well-known causes for coughing like airway infection, asthma, post-nasal drip, chronic obstructive pulmonary disease (COPD), gastroesophageal reflux disease, cancer, alveolitis, heart failure or medication with angiotensin-converting enzyme (ACE) inhibitors, there is still a group of patients left over with chronic cough without a specific diagnosis having an ongoing cough, often refractory to available cough medications. Here, ACE is linked to hypersensitivity pneumonitis.